Personally, I think tank swaps are kind of lame and the least interesting way to pretend 2 tanks is necessary for a full party. That said, OT absolutely could use more to do. Luckily at this point we actually have a lot of standardized mechanics we could take advantage of to keep the OT engaged without making them count stacks on MT. Dual tank busters (each get their own), double tank busters (both need to share the same one), tank towers, laser/wild charge mechanics they need to be in front of the party for, flare markers they need to be away from the party for. And if the latter three overlap with MT getting their own tank buster, all the better. There's also the much more obvious option of simply bringing back adds into fights, which... I have no idea why we ever stopped doing that. They could also make use of multi-target fights again, like in some of the earlier coils or O12. They could even start putting DPS busters on the party that the OT should be paying attention and using their target-able short mitigations on.

Honestly, there's so much stuff they could be doing to keep the second tank engaged, instead of just being a gimped dps that can ignore vuln stacks. Luckily this new raid tier for 7.0 seemed a bit better about that than the last few have been though, so here's hoping they'll continue expanding on that as we go.