There are a couple of things you wrote that I want to get a bit further into, but to start with:
while I don't find much appeal in steampunk culture past its colour palette and the occasional whimsical machine that actually functions, I have no issue with historical reimaginings
I think I'm with you there. I don't see steampunk as cohesive other than as sort of a fantasy-enhanced Victoriana. It seems to be centered around dressing up for conventions or other pop/alt cultural events. There's a whole topic of conversation in itself - the way that costumed clans have grown into whole social scenes within the Comics/SF&F Convention world. It has a kinship to the Goth scene, but is less club-going and more about conventions. The style is more costume than clothing. I guess I think of Goth as a fashion/mindset and Steampunk as a pose, or a kind of play.
There is also a connection to the contemporary maker scene, with custom clothing and jewelry making as major focuses of activity. Search "Steampunk" on Etsy and you'll have plenty to look at. There are the occasional clever devices that actually function in some way, as you mention, but mostly it's just cobbled together brass, wood and gears to give a mechanical feel. In some ways I find it depressing; a large amount of effort is put into assembling broken junk into non-functional meta-junk.
Steampunk is people like the League of Steam who mainly build imaginary ghost-hunting devices and maintain a kind of ongoing performance art existence as characters from an imaginary past. But then look at the the people at the Science Museum in London who built an actual, functioning Babbage Engine*. Most of us wouldn't call them "steampunk" as they don't play in the aesthetic, but what they've built is an honest, functioning steam era mechanical computer. They essentially made an alternate-history science fictional device that actually works.
I guess I shouldn't discount the value of the aesthetic as play. Science Fiction as a literary genre itself is a codified form of make-believe. But I think there is a continuum of play here, with ideas at one pole and aesthetics at the other. Today steampunk has drifted pretty far toward the latter, and I'd like it better, I think, if it were closer to the former.
*Allana has a post that deals with the Babbage Engine coming up, so I kind of stole some thunder here... sorry! I just needed it to draw a proper contrast. I will try not to do that again!