A direct drive sounds good but a "normal" servo is perfectly adequate for my needs, simple to fit and can be fitted above or below the table. If it needs to be replaced virtually any servo can be slotted in. It also allows a speed reducer to be fitted, which will give slower speed with increased torque, something you can't do with a direct drive. My servos can also be easily swapped amongst my machines, if needed, something I couldn't do with a DD.
A DD certainly looks neat but adapting one to older machines could be a bit of a pain and from my perspective not worth the trouble. It would be an interesting exercise to try setting one up but I'm happy with my setup(s) so I'm not about to try. For a garment machine they may very well be a great solution but I'm not convinced about their suitability for leatherwork.
Just my thoughts on the subject.