Looking at who was available, and the money they got, I definitely think we made the right decision.
Probably. I think there's about a 30% chance that we will end up wishing we had Dampier instead of Nash.
The Suns currently have the rights to four point guards: Nash, Barbosa, Tabuse, and Vujanic (if he is still considered a PG). Nash is obviously the best of the four, but if he were gone, the Suns would survive. Their backup PG contingent is better than the current army of centers. And Johnson has shown he can be a pretty effective floor general too.
Assuming the Suns were going to sign Richardson anyway, they could have had this lineup:
C - Dampier/Voskuhl/Lampe
PF - Stoudemire/Lampe/Vroman
SF - Marion/Cabarkapa/Johnson
SG - Johnson/Richardson
PG - Barbosa/Johnson/Tabuse
It's not the offensive juggernaut of the current Suns team, but it's a lot stronger defensively, and it won't constantly reek of small ball.
If Dampier is a bust in Dallas, then obviously the Suns made the right decision. We'll have to wait and see.