To answer the title question I wouldn't say I hate them, I just don't dig them.
Theyre something to be used in addition to road miles, not as a substitute. "Mile" for mile they don't provide the same level of workout as actually riding, and they very quickly allow control skills, roadcraft (and racecraft) and situational awareness to degrade.
When the first rays of spring arrive one only has to see the appalling manner in which club riders wobble all over the carriageway to see the end result of a diet of indoor riding to the exclusion of all else. Indeed, in the lockdown TDF of 2020 it was very apparent who had done the indoor miles and who had done the tarmac miles.
And their very use by many presents a quandry. Folk complain they don't like the wet, cold, ice, marauding werewolves, etc, so prefer the indoor workout. All well and good, but if your riding and/or fitness is that important that you want to keep training then those challenge are actually seriously good tools to improve your fitness, endutance, environmental tolerance and skills.
Use in moderation as part of a calorie controlled diet and not, as far too many sadly do, as a means of sustenance all on its own.
In short, I'm not against them per se but more the manner in which many folk decide to use them.