We're not trashing "cheap" lenses per se; only when they're not only cheap but also bad.
Nobody would say any bad words about the 40/2.8 STM for example which is truly inexpensive but at the same time has great quality going for it.
Bright Colors: I know it's not great, but I got my 75-300 IS USM in new condition cheap with the hood so I can live with it. I believe it was the first implementation of IS, so it is a also, I suppose the worst. Still always surprises me to hear how terrible certain lenses are considered. Looking at the lens designs, it is almost identical to the 70-300 IS USM that replaced it. Both only have micro-motors, and are rather slow. There is one of the smaller interior elements that was made of UD glass, and some slight changes to a couple of the elements. But people seem to be fine with that lens!
Rover, I do understand. I have been eyeing the 40/2.8 STM and the EF-s 24/2.8 STM. I know it would be nice to have upward mobility in my lenses ( to FF), but after years of crying "foul"! because Canon was not doing enough in EF-s, I actually appreciate the 24mm lens being made available!
Toni-a: I see the problem. It seems like something should be salvageable, but it doesn't seem too likely.
Thanks for your responses, gentlemen! Sorry if I am oversensitive with my 75-300!
I remember reading...it seemed to me he said if he already had the 75-300 it wasn't enough difference that he would change. I do care about sharpness, but I find most of the time I am using the lens, I'm using it at 300mm anyway, so have I am thinking about get the 300mm F/4L IS. Because I use a 70D and prefer the 55-250mm STM the only reason I keep it is for when I get a FF. But this discussion is making me think, better to put it towards the 300 prime.
I appreciate your comments everyone. You have helped me think this through!
If you aren't using a high pixel sensor then 75-300 is ok. On 30D almost all my lenses were fine, using 750D suddenly everything changed.