In World War II, as opposed to World War I, there was much more of a drive to keep a distinct Canadian identity on the battlefield. The action you mention was part of that drive.
Pierre Berton's Marching as to War, among other works, argues that shifts in the Canadian political and social viewpoint during the interwar period made for a country much more independent of the British Empire and interested in a military much more separate of that empire.
This resulted in distinct equipment, distinct training, and a desire for distinct leadership. While there was a Canadian Corps in WWI, it was very much subservient to the British command structure until the last year of the war. In WWII, there was no desire to repeat that process.
That's why Canada acted differently in WWII, sending soldiers as whole regiments, operating the No. 6 (Royal Canadian Air Force) Group, and maintaining as independent a command as possible within the overall Allied effort.
I'll answer the question to the best of knowledge, I'll try and provide sources when I can get to them. But first I'll post a response that I gave to someone who asked a very similar question about the Canadian artillery officers in the First World War highlighting why the Canadians did not have as much of a national identity in the First, as they did in the Second World War as u/The_Alaskan pointed out.
"Due to emigration from Britain, a large number of Canadians at the outbreak of the First World War were born in Britain. Up until, and during the First World War, many Canadians considered themselves British and saw Canada as a British part of North America. Although I have no idea of the exact numbers of British officers that were officers in the RCA, you would most likely be correct in assuming that they were. After all, at the outbreak of the war, the Canadian Army numbered less than 5,000 men, so as you can see, there is little space for an experienced Artillery officer corps. The British Army on the otherhand had a relatively large number of Artillery officers at the outbreak of the war, and as the Canadian Army was facing massive expansion, it would have been wise to second a number of officers to oversee the rapid expansion of the RCA to allow them to be an effective force, and also ensure gunnery training was up to scratch."<
So as you can see, The Canadians did not really have the infrastructure in place for large formations. The Canadians actually authorised the creation of 260 infantry battalions for the CEF. We must also remember that it was not until 1940 that the land force of Canada was actually called the Canadian Army, its official name was the Permanent Active Militia prior to this. Until 1914, the PAM consisted of one infantry, and two cavalry regiments, so we can see that the standing forc that the Canadians possessed was rather small.
Now back to the CEF! The CEF was a completely different land force than the PAM and came under a different command structure as it reported to a separate government ministry, the Ministry of Overseas Forces of Canada. And due to the rapid expansion of this new force, a temporary force, and one different to the existing military structure, it was seen as more prudent to raise numbered infantry battalions as opposed to creating new named regiments, or adding battalions to the Militia, which had been mobilised for the defence of Canada only. However there were two named infantry battalions as part of the CEF, the Royal Canadian Regiment, and Princess Patricia's Canadian Light Infantry which were now part of the CEF instead of the PAM.
Now onto the Second World War and the chance to Regiments! After the First World War the CEF went through the demobilisation process and disbanded. Along with this process was 'The Otter Committee' which was tasked with reorganising the PAM and Canadian Militia (Reserve Force) into a more modern force. It recognised the traditions of the militia and also the battle honours won by the CEF throughout the First World War, it then made the decision to integrate these hard won battle honours into the Regiments of the PAM and Militia, this led to Canada restructuring its armed forces in 1936 to mirror the British Army and ensure that it had the basic infrastructure in place for mass mobilisation, this is shown when in 1939 Canada did mobilise her forces. Due to the mobilisation of the PAM and Militia, as opposed to the creation of a new CEF, the Regiments were expanded and kept their identities throughout the war, with battalions being added to existing Regiments when the need arose.
Apologies for any grammatical errors and lack of sources, trains unfortunately do not come with well stocked libraries! But hopefully this answers the question, this is a bit of a whistle stop tour of the Canadian military, if you would like some sources please let me know and I'll be happy to provide them!
While the growing desire for social independence certainly played a part through changes in organization of the Canadian Army, I do not believe that it directly impacts this question. Canada has always used named regiments, and the separately numbered battalions of the CEF was an aberration.
In 1914 Canada was not prepared to provide a large expeditionary force. It had two mutually exclusive mobilization plans. A general mobilization plan based around the ~130 existing Non-Permanent Active Militia regiments (~1000 men each) to be formed into 3-4 battalions (~6000 men each) for the defense of Canada proper, largely in event of American attack. The second option was a temporary and limited expeditionary force plan which would raise up to one of those battalions ad hoc using volunteers from the existing regiments.
For reasons that are difficult not to editorialize as he is an extremely controversial figure, the Minister for the Militia Samuel Hughes decided to forgo the general mobilization plan and instead expand the Expeditionary Forces into a general mobilization. This resulted in the creation of the numbered battalions of ~1000 men to be organized into divisions of ~6000 men, using the contemporary British naming system to avoid confusion. The exceptions were the Permanent Force units (RCR, Lord Strathcona's Horse, Etc.) and the PPCLI who were raised privately and fought separately in the British Army for the first year of the war. A separate ministry, the Ministry of Overseas Forces of Canada, was created in 1916 ostensibly to manage the separate force. The Expeditionary Force was disbanded at the end of the war.
Between the wars, Canada reorganized the militia in 1920 and 1936 which, aside from disbanding or combining around half of the Militia units, removed the Expeditionary Force organization to modernize the prewar regimental system. This was intended to prevent the difficulties associated with raising ad hoc units. Units raised in the expansion of the army after the fall of France followed this pattern, largely reinstating the names of units from before 1936 or the CEF.
Sources: Canada's Army - JL Granatsein Canadian Expeditionary Force, 1914-1919 - GWL Nicholson