There is no specific reason why the B10TL got the suspension system.
The suspension system has been a standard fit to Volvo low floor chassis
way back to the production of B10BLE (I don't know if B10L has the same
system). Given the B10TL shares the same front module, and hence the
suspension system with the B10BLE and the newer B7L range, it received
the suspension adjustment system as well.
The suspension adjustment system (cannot find a better way to call it)
has been a standard fit to many European productions, including Volvo,
VDL Bus, NeoMAN, Mercedes and Scania, to name a few.