Fordronken, I understand if you project future salaries and their impact into the future, the Suns, sooner or later, get their hands tied (especially if they sign a player with a higher salary like Wilcox). I understand and accept this logic if all things remained the same for the Suns and other teams in the NBA. However, all things change and do not remain static and I think (and you probably do as well) that the Suns roster will change several times over the next few years and that perhaps a core player may have to be moved. My logic, which IMO is really not contradictory to yours, is to assemble the best team available now (within reason) and move the least essential part next season or when the needs arises.
If the Suns sign good players to reasonable contracts, the Suns should be able to move such contracts in the future if needed. In regard to Diaw and Barbosa, if their salaries are extended they would not impact the Suns this coming season. My logic, if I'm the Suns, if you have quality players under contract (Diaw and Barbosa) that can within reason be extended for hopefully less (but no more than market value)... do it now.
Then if the Suns win a Championship next season, we may not need to dump contracts (because of increased supplemental revenue) or if the Suns do need to get rid of a contract or two, it is not hard to trade quality players. Also the Suns, IMO, are not going to use all three first round draft picks. I think they will use at least one, if necessary, to move a player.
My thought process is really the old market concepts of if you buy quality you have quality and the concept of buy low and sell high combined.
So if I'm the Suns, if I could add a player which I think would give the Suns a high probability of winning a Championship this coming season I would worry about what player may have to be moved next season.
My Personal Opinion: I would add a pick with KT and try to move him now for a young 4/5 like Wilcox, Gooden, Jeffries or whoever D'Antoni likes for the Suns and this lessens the financial burden for the Suns (or advoids the luxury tax for a couple seasons) and allows for the Suns to add a young 4/5. The Suns would also gain an additional year to consider who they may want to move or keep on their roster for the future as KT is still under contract at a significant salary for two seasons.