Huh. I mean, sure, a lot of the sidegrade suggestions end up irrelevant - do I want to swap improved armor for improved shields on one of my freighters? Nah, don't care.
...But definitely not all of them. Will I swap improved armor for reduced supply usage on a freighter? Absolutely.
(And even for main combat ships - am I going to trade out 'Deadly' for anything else? Almost certainly not.)
...That said, there
are situations where the 'new traits' messages can get spammy: if you just purchased or recovered a bunch of new ships all at once, then it takes very little XP to get their first set of traits, and I frequently see that trigger off exploration. Still, that's kindof a niche case, and it doesn't really bother me that much.
If I understand the feature correctly, you have to click through one proposal to get the next one, which adds tedium.
I'm pretty sure you're not understanding the feature correctly? At least, if it offers a sidegrade I don't care about, there doesn't seem to be any penalty from just letting it expire rather than tracking it down and explicitly saying 'no thanks'.