Just corporate procedure and trying to save busy-work.
At the same time, the other company was willing to do that extra work upfront, which made me feel like they actually wanted me to come.
I think I might've felt a little differently about it had the recruiter been transparent and said something about the work involved. Then again, at the end of the day, we had all done quite a lot of work to get to that point. Not being willing to do the final steps suggests (to me) a lack of commitment to the offer.
1: there is something materially and surprisingly bad in the contract (equity or cash isn't as described)
2: there is something that is arguably not material, but which is surprisingly bad in the contract (something to do with vesting schedule, clawback of a 'signing bonus')
3: everything is as-expected.
In case 1, it's clear that they have materially changed the terms, and I am no longer bound by my verbal acceptance (which was of a different offer).
In case 2, they can argue that what was changed isn't material, and so I'm still bound. But if they say that, I would reply that if it's not material, then they should have no problem changing it back to the originally-discussed state. If they don't, I walk. It's not like they can force you to work for them, and they would presumably not try to ruin your rep over it because you could probably do more damage to them (by posting on HN, for example).
In case 3, obviously everything is fine!