Fermentation temperature questions.

I have read and listened to a bunch of posts, comments and stuff about fermentation temperatures, Brewpis and that kinda stuff. I also lurk here A LOT.

To tell you the truth, this weekend, I will be brewing my 75th recipe and I have never used any of that. All my brews have been BIAB, started at 1ish gallon, now at 5ish gallons.

I have a room that is at about 18C (65F) in the summer and about 12C (54F) in the winter and a second one that is about 4-8C (39 - 47F) in the winter and 18-25 (65 - 77F) in the summer.

I just put my fermenters in a water bucket for temperature stability.

I have gone through a lot of "phases" in my brewing where I have experimented with having half in each room at different times of the year. I have never really noticed any differences in taste when using the same yeast (both lager and ale) but do notice a huge difference between the two (ale yeast and lager yeast). Keep in mind these are not controlled tests, just me and some friends drinking my beer.

I often see posts saying they saw a huge difference when getting temperature control unit and I am sceptical. What are those differences? What got better in your beer when you got ferm temp control? Is there a point to all those complicated temperature schedules beyond "because that's how it's done"? Any chemical composition data?

Cheers!