Parry mechanics did change quite a bit. Now a parry costs a LOT of extra stamina, making it a strategic choice rather than a timing skill. The wiki has more details, but in general stronger shields should absorb more damage while costing less stamina.

Tower shields don't seem to have any particular blocking bonus. They can absorb a bit more damage for less stamina, but that's it. Maybe the loss of parry is an actual bonus, but the speed penalty is very dire for what it gives.