I dunno - I dislike the idea of them getting bonus heritage feats because to me, that just ends up reinforcing the theme that they must be descended from some exotic power, and I hated the way wotc tried to tie just about every sorc to some draconic ancestor.
But that's just me.
Well, first of all, I actually dock them 1 spell per level. No worries, though, because it gets replaced with the bonus spell that the bonus DCv1 Bloodline Feats provide.
Second, the Bloodline feats cover a wide variety of ancestries- elementals, celestial, infernal, fey, illithid, undead

erm

and so forth, including dragons. IOW, Sorcerers are delivered from being linked to dragons exclusively.
Third, it gives a mechanical justification for their being innately gifted with arcane spellcasting ability. He can do something normal human(oid)s can do- cast arcane spells without studying to do so- because he's more than human(oid).
The subsequent heritage feats, however, must be taken as normal, if any are taken at all.