But I think a much more important problem is that devs can't force everyone to use drivechains due to the decentralized model of bitcoin, by pushing a new bitcoin core release.
I wouldn't say that's the real problem of drivechains.
My understanding is that drivechains are soft forked into the main chain consensus. This means two things: Non-upgraded Bitcoin nodes would no longer be fully validating, and fully validating Bitcoin nodes would now have greater bandwidth, latency, and storage overheads. Just like block size increases, this would negatively affect miner and full node decentralization.
Those costs probably aren't worth the gains given how insecure a drivechain is,
by Paul Sztorc's own admission:
It is said that 51% of the miners can steal all of the funds on the sidechain.
It is true that 51% hashrate can overwhelm the 13,150 ACK requirement (ie, the train metaphor), and (if unopposed) include any withdrawal they like. Namely, they would include a withdrawal that pays them all of the sidechains BTC.
A 51% attack on Bitcoin only allows miners to double spend. On a drivechain, they can just steal everything.