Interestingly, during the late 19th/early 20th century in Europe, there were significant pendulum swings regarding attitudes to technology. It wasn't all positive-- far from it.

As industrialization swept Western Europe, there were major pushes towards a view of the future and technology as a glamorous, exciting thing. One obvious example of this attitude were the various "exhibitions" put on by major European cities: London's [Great Exhibition of the Works of Industry of All Nations] (https://books.google.ca/books?id=19wY8iof5ywC&printsec=frontcover&dq=1851+exhibition&hl=en&sa=X&ved=0ahUKEwigj5T22-LPAhWO14MKHaiHCNwQ6AEIJDAB#v=onepage&q=1851%20exhibition&f=false) in 1851 was not the first world's fair but was the most prominent early example, followed up with Paris' [Exposition Universelle] (http://www.expositions-universelles.fr/1855-exposition-universelle-paris.html)-- link in French, sorry-- in 1855, and again in London in [1862.] (https://archive.org/stream/1862appletonsan02newyuoft#page/n420/mode/1up) In fact, these exhibitions were not limited to Western Europe, with both Japan and Peru hosting fairs in the 19th century; however, they were concentrated there.

These were not small events. The 1851 exhibition was attended by six million people, which was about a third of Britain's population at the time! They demonstrated the hottest technological innovations of the day, including the first ever modern indoor toilets, and the precursor to the fax machine. Jules Verne attended the 1867 fair in Paris and was apparently so enraptured by the demonstrations of electricity that he wrote 20,000 Leagues Under the Sea shortly thereafter. You can see the brochure for that exhibition [here] (https://archive.org/details/lexpositionunive01expo) again en francais, desolee-- it gives you a sense of the scale of the exhibits.

These fairs were not simply an expression of technological accomplishment; they were also demonstrations of Imperial power. Diamonds from British India were put on display, and cultural costumes from "exotic" nations were modeled. There were also associated events like [human zoos] (https://en.wikipedia.org/wiki/Human_zoo) which, while horrifying in the modern context, help to illustrate attitudes held in the 19th century. Many of those held captive on display in these "zoos" were presented as an example of "earlier man," an "unevolved" person who did not have the benefit of all this wonderful technology. The relationship between industrial technology and colonial racism is important and shouldn't be overlooked, which I think also touches on your original question.

In the early 20th century, optimism about technology persisted. Attitudes are not always so easy to observe, but we can look at some artistic movements as evidence of that thought. In 1909, in Italy, the Futurist movement began with a [manifesto] (http://www.unknown.nu/futurism/manifesto.html). It was the boldly pro-technology, anti-traditionalist philosophy of its time.

It is from Italy that we launch through the world this violently upsetting incendiary manifesto of ours. With it, today, we establish Futurism, because we want to free this land from its smelly gangrene of professors, archaeologists, ciceroni and antiquarians. For too long has Italy been a dealer in second-hand clothes. We mean to free her from the numberless museums that cover her like so many graveyards.

Museums: cemeteries!... Identical, surely, in the sinister promiscuity of so many bodies unknown to one another. Museums: public dormitories where one lies forever beside hated or unknown beings. Museums: absurd abattoirs of painters and sculptors ferociously slaughtering each other with color-blows and line-blows, the length of the fought-over walls!

The whole thing is well worth reading, but where it becomes particularly significant is the Futurist attitude to war:

We will glorify war—the world’s only hygiene—militarism, patriotism, the destructive gesture of freedom-bringers, beautiful ideas worth dying for, and scorn for woman.

As you might imagine, this attitude in 1909 wouldn't last the decade. Literally glorifying war didn't stay popular at the arrival of WWI, where the advances of the past century suddenly made killing many, many, many people terrifyingly easy. I am not an expert on warfare so I won't comment too much, but technological innovation brought about the development of many new devastating weapons. Flamethrowers, mustard gas, effective machine guns, grenades, mortar shells, tanks: these all saw their broadest debut during WWI. [More information here.] (http://www.firstworldwar.com/weaponry/) Obviously, the carnage was enormous on an unthinkable scale, with 11 million soldiers estimated to have been killed. The Futurist Movement in its first form (there was a later wave in the 1920s and 1930s) effectively ended in 1915, and many of the extreme Avant-Garde painters and artists participated in a movement after WWI called the [Return to Order.] (http://www.tate.org.uk/learn/online-resources/glossary/r/return-to-order)

Simply put, technology could no longer be venerated as an absolute answer to humanity's problems when it had facilitated the largest mass slaughter in human history. Futurism gave way to [Dada] (http://www.tate.org.uk/learn/online-resources/glossary/d/dada), art born from the powerful and haunting sense that the promised beauty of technology wasn't real, and that frankly, the future didn't make much sense.

I will leave the question of WWII to those with more knowledge of the field, but there were many similar revelations with the horrors technology inflicted during that war, namely: the Holocaust (impossible without railroads, gas as suffocation agent, and the idea of a "War Machine") and, of course, the dropping of the atomic bombs on Hiroshima and Nagasaki.

The inventor of those bombs, Dr. Oppenheimer, is famously quoted as having thought of a verse from the holy Hindu book Bhagavad Gita

"kālo'smi lokakṣayakṛtpravṛddho lokānsamāhartumiha pravṛttaḥ" (XI,32), which he translated as "I am become Death, the destroyer of worlds." (Jungk, Robert (1958). Brighter than a Thousand Suns: A Personal History of the Atomic Scientists. New York: Harcourt Brace. ISBN 0-15-614150-7. OCLC 181321.)

There are more examples, but this is an important timeline to follow. While the 20th century heralded enormous technological innovations, it was also the century that demonstrated-- with body counts in the tens of millions-- the destructive power of technology.

So to answer your question simply: no, people are not always optimistic about technology, but it's usually been in the wake of very destructive technology.