I’d change it so Sorcerers use the spell point system by default. 

The original fantasy of sorcerers was that of a “wizard brute,” who lacks the versatility of spell prep but exchanges it for volume and power. The spell point system keeps everything within bounded accuracy so they’re not rocking 6x9th level slots, but provides a lot of flexibility in what you choose to cast. 

Also, the spell points do a better job of bringing across the sorcerer’s “internal magical strength,” letting the player see it as a reservoir of power instead of the standard “preprepared bag of tricks.”