right now, bards and invokers are the only arcane caster classes lacking the Summon Familiar feat
i think it'd be nice for RP if they could have familiars, and with the introduction of runic sequencers (as well as familiars not being very powerful to begin with), i don't see it being a huge deal in terms of balance?
additionally: bards should perhaps receive their familiars at a later level, the same as warlocks, so as to not force countless bard dips to relevel!