There was a lot of bad stuff at that time, sure, but logically, why is that specific time period seen as so bleak as opposed to 50 years before, when they were more diseases, deaths, and general unpleasantries? Are there examples of text from that time that were reflective of this sentiment, or is this entirely a contemporary viewpoint?
There's certainly more that can be said, but you may be interested in a previous answer of mine where I discuss twentieth century views of the Victorians:
Why are people today fascinated with the Victorian era?
In particular,
"Victorian" has come to mean a lot of things beyond "relating to the reign of Victoria, 1837-1901": broadly speaking, things that are recognizably not "modern", the way that we see ourselves or would like to be seen. This started relatively soon after the end of the queen's reign, with those in the late 1910s and 1920s seeing themselves as part of a "post-Victorian" age that was starkly different from what had come before. This has largely been studied in the context of early twentieth century writers like those of the Bloomsbury Group - Virginia Woolf, Vita Sackville-West, T. S. Eliot, et al. - who distinguished themselves or who were distinguished by others as being intentionally anti-Victorian, or whose pro-Victorian sentiments need to be examined beyond simply being considered conservatism. These writers generally came of age around the turn of the century, spent their childhoods in middle- or upper-class Victorian households, and went on to become an educated, elite group that conspicuously spurned the mores and standards of their parents' generation, which to them represented the whole of the Victorian era despite being a highly skewed view of the entire period and all of the people in it.
Twentieth century views of the era conformed more and more to that of the Bloomsbury Group as "moderns" opposed themselves to the Victorians, who were now the Other. They covered up piano legs for modesty (they didn't: that was a joke printed in 1839 about specifically American squeamishness that somehow got legs (please excuse the pun but I couldn't help myself)), we wear skirts that come to just below the knee or mid-calf. They forced women into horrible, tight corsets, we wear elasticated girdles and/or diet to stay in shape. They kept women oppressed and immured in the house, we totally allow them to work
sort of. Flaws of current times were smoothly papered over or not actually noticed at all, while those of the past, particularly those that had been highlighted in nineteenth century fiction, were magnified and presented as relics. In 1948, a reviewer for the London Standard astutely noted:
Sustained by countless novels and plays and eagerly seized on by the makers of films is the Great Victorian Myth. The Myth has almost succeeded in converting the younger generation to a belief that Victorian domestic life was full of thwarted motherhood, tyrannical husbands and fathers, and spiritual frustration in dark, rambling houses. ... Clearly the thing to do was to torture the heroine, and if you put her in crinolines you could torture her much more severely.