"Need" is a strong word. And BB-8 being pulled in multiple directions isn't really a matter of there not being enough droids in the game. It's a combination of factors.
There are already enough droids to make a great Grievous droids team without BB-8 for TW/GA, putting him back with JTR. And those are the only two directions BB-8 is pulled in any meaningful way for those game modes. More droids really wouldn't alleviate the choice between Grievous nuke versus anything else considering what BB-8 provides is the ability to outspeed literally anything but Han/Wat.
The only other case they're really pulled in different directions is whether to use BB-8 for P1 JTR or P3 CLS in hSith, which more droids wouldn't help with because the uses for BB-8 are the specific Resistance synergies, either fueling JTR and giving Illuminated Destiny or calling 3PO to assist ad infinitum.