From what I’ve noticed, the slow pace with Taproot mostly comes down to how much backend work exchanges would need to redo. It’s really not as simple as "enable Taproot”. They will have to adjust parts of their key-management systems, signing setups and a bunch of security routines they’ve relied on for years. Most big platforms avoid touching those unless there’s a strong reason and since SegWit already works smoothly for most people, there isn’t much pressure on them to rush anything.

I honestly think Taproot adoption will pick up naturally once more wallets, libraries and multisig tools make Taproot support easier by default.