For Shinobi case, I think it's intentional that they are giving such a not-interesting reward for SEGA account.
They are also selling Digital Deluxe upgrade contents afterall.
All the good things (including the arcade original outfit) would be put into the Digital Deluxe upgrade + pre-order bonuses since it would make us throw more money to them.

The ghost outfit looks so much cooler than just
blue. The ghost outfit is also blue.
But i still stand by what i said about how they should re-introduce/overhaul Avatars as a Sega Account+Official Sonic feature. Not just to allow us to play as our Sonic OCs in future Sonic games, but in the same way Mii's represent Nintendo accounts or XBox Live Avatars represent XBox accounts.