I'm afraid I can't speak to exactly why there was a change in Academy Award ceremony dates and eligibility periods, but it's worth pointing out something that you haven't mentioned in your question which I think you might have missed: although there was no ceremony held in 1933, that doesn't mean there was a period (either in 1933 or 1932) where no films released were considered for awards.

The 5th Academy Awards ceremony (the one held in 1932) was, like the previous two ceremonies, held in November, and it honoured films released in the 12 months between August 1931 and July 1932. People familiar with the modern Oscars might find this surprising, as everyone knows that nowadays, each award ceremony relates to a single calendar year of film releases (i.e. the 92nd Academy Awards ceremony, held in February 2020, honoured films released in 2019). The 7th Awards was when this started, and the 6th - the one you're asking about - covered the transition period

Perhaps the Academy in the early-'30s thought that it would make more sense (i.e. be better for marketing) for each ceremony to relate to a single year's worth of film releases, or perhaps there was another reason the ceremony had to be pushed back, but either way, the 6th Academy Award ceremony was held in March 1934, and honoured films released in the 17 months from August 1932 to the end of December 1933. This meant that no films released in late 1932 (and therefore ineligible for the 5th Awards) were overlooked, and that in future, each ceremony could cover 12 months of releases from a single year.

Hopefully, someone else can chip in with more detail about the Academy's actual decision making process.