Pretty much this. Like the lumber mill (arguably the worst medium building), you can do it once on one character to get all the achievements and stuff and never touch it again. The inn is really handy at first. It is useufl for my alts, though, because I don't necessarily feel like collecting every follower I have on my main unless they are already max level or rare to start with at the very least. So you get a new follower every week with a trait of your choosing + a free Millhouse when he shows up which is a nice bonus. After you've done all that, then yeah, maybe another building will prove more useful. The barn is a pretty good medium building to have, the rewards are well worth the effort you put in, at the moment at least.
"Severely lacking" seems a bit dramatic.
There are several toys and other fun items, along with the upgraded Crystal item which is pretty useful. The lvl 3 gold missions great - yeah, they aren't thousands of gold but they are free gold and I never have enough missions to send my followers out on anyway. Why wouldn't I take the free gold? I'll continue to recruit followers weekly as well.
Yeah, you probably don't need or want to keep running the dailies after you've gotten the lvl 3 achievement and the toys/items you want. But so what? I wouldn't want a reason to have to keep running heroics after I've outgeared them. The Inn has accomplished its purpose and it continues to give me followers and gold every week. Most Garrison buildings are more useful at first, and that tapers off as you've upgraded them and gotten stuff that you need. There's a trade-off to all of them, but I'll be sticking with my Inn for the foreseeable future. Right now my other building is a lvl 1 Glad sanctum as I wanted to get some PVP gear, but now that I've gotten what I needed I'll probably trade that in for a Trading Post. I don't need the GR that the LM would provide, and while the prices of Savage Bloods would make me more each day through the Barn, that would also require more time/effort to go out and trap the elites and I'm already doing that on an alt so I have no interest in doing it more.
The long-term value in most of the garrison buildings is pretty subjective - many of us will want to change around buildings to get some of the achievements and early benefits like recruiting followers, or the stable mounts, or PVP gear, or unlock the rep faction in the Trading Post, etc etc but once we've done that then the buildings we will keep just depend on our priorities. I have no reason to replace the Inn because the other buildings don't give me anything I care about more than the free gold and the extra followers.
I had an inn for about 15 minutes, before realizing that I was going to have to continue running dungeons to make it worthwhile. (it was early, hadn't had my coffee yet)
Out came the bulldozers.
Assuming you have a salvage yard (why wouldn't you?), each quest also grants a salvage crate.
I would not delete any building so far. Just look at the Garrison map ( if you play Horde ), then take a look at the center where all the small buildings are and then at the Northwest portion within your walls. Plenty of space to put one small building in the middle + a medium (and Large) in the open space in the corner.
no more or less rewarding than any other building. Leaving aside personal priorities which will change the weights.
at this point, once you get all the toys. the dailies are just a rather nifty dungeon bonus. no need to focus on doing them. just pick them up every day and do randoms, you'll eventually cross paths.
That flask one is really nice too. IMO the real appeal of the building is the headhunter and the treasure missions. Treasure missions usually don't award much gold but they're a huge boost to the amount of big salvage crates you'll get, especially with the extra l100 missions. Not too wild about the building on alts beyond getting the first few scavs, don't see myself keeping it long term there because I'm not taking the follower minigame seriously on alts. I view it as a follower boosting building, like the Salvage and Bunker, so if that's your thing, you might want to pick it