The second pick was a roster slot issue. D'Antoni wanted veterans on the deep bench rather than projects. That may be short sighted, but hardly irrational.
I can see where your coming from on this, however, I do not think the roster filler veterans on the Suns team (Burke, EP and Marks) are going to help the Suns much more than a rookie. I think the Suns just wanted to save some salary by not giving a first round draft pick a guaranteed salary for more than one year and also the Suns probably liked the idea of having the league subsidize one or more of the veteran minimum type salaries.
I hardly think the elite veterans mentioned above are going to help the Suns win a Championship. However, I do think Jumaine Jones can help the Suns if healthy.
Just another thought. If all the money the Suns saved by not signing TT went for signing Banks, where did the 3 million go from selling the latter draft pick? I mean the Suns have to carry a full roster and Jumaine Jones signed for the minimum.
Maybe the Suns saved it to help extend Diaw. I think the extra 3 million would help make up for the 10 million the Suns and Diaw are reportedly apart on contract negotiations... especially if they split the difference. If splitting the difference would get it done, all the Suns would need to kick in is only 2 million more (3+2=5).