What do you mean exactly by "lower status" ? Do they lower the perceived status of the writer, or do they convey the idea that the reader has lower status than the writer ?

Exclamation marks friendliness, "it'd be great if" and "Thanks!" I'd perceive as somewhat condescending in an email exchange with someone I didn't know well, whereas "you don't have to do this but" and "sorry to bother you" I'd read as delaying expressions and thus status-lowering for the writer.

But again, it's a matter of context. In an informal email exchange I wouldn't worry too much about these things.