I don't mind if a BL couple has preferences and stick to them, either.
I only get irritated/bored by the BL stories where it's like being the seme is a matter of pride and being the uke is shameful and submissive and they argue over it (and especially when the seme is like - you have to submit but hell if I'm gonnna). Those ones I'm a bit sick of.
Yeah, I think that'd be believable. Personally, I don't like other manga where there'll be a whole chapter or even the whole story revolving around who tops like being the uke is shameful so they'll make the person they're supposed to love do it instead. I agree that some general hesitation or uncertainty could be normal.
Yes , though I read a few manga that they take turns I believe ? though there aren't many manga of that kind? But in one of them I remember in the end one of them just didn't care anymore as long as they are together(づ ̄ ³ ̄)づ I read it a couple of times but i don't remember much about it ╮( ̄▽ ̄)╭ but I do remember that I liked the change , like you said no one was shaming the other about being the bottom,well then ヾ(☆▽☆) oh and most of the times the seme is a jerk so I don't mind if the uke doesn't top , I don't want him to turn into a jerk or something hehehehe ( ̄∇ ̄") I'd want to beat the hell outta hím and break them :)

This was really moe for me, both of them were really adorable. As for the switching (or lack thereof), it didn't both me. BL at it's core is very shoujo manga, it's hard for people to switch their pairings (even if switching is reality).