This thread reminds me of similar ones done in previous years about how the Celtics absolutely had to find playing time for Shav Randolph and Terrence Williams and Sean Williams and Dario Milicic and so forth and so on. Where did all those guys end up? My guess is Powell ends up in the same place
Not sure why you're bringing Shav Randolph an Darko to this discussion. Shav deserved the playing time he got and earned it, he was cut from the Celtics purely because of financial reasons (we were cutting costs, and he was a non-guaranteed contract). He's currently on the Sun's roster for whatever that's worth.
Darko simply got injured and who knows what the heck happened behind the scenes between him, the coaching staff, and the organization... but he was a legit NBA player, for all his faults (more so because of the unrealistic expectations on his rookie year), he's a very good defensive big man and a rebounder, to say nothing of his passing skills. So yes, calling for his playing time was more than warranted and he would've been a difference maker on our team that year had he remained healthy (and who knows what else occurred that prevented him from staying around). Or you know, we could just start Jason Collins...
Comparing these players to the reaction some have for seeing a rookie play for the first time is a bit mind boggling.
Edit:
We can go on... Terrence Williams, well he had the whole gun arrest issue, so that has nothing to do with basketball.
Sean Williams... well, whatever... I don't care enough about him. He's a moron and didn't deserve any playing time.
I'm not comparing these players as rookies but as end of the bench, barely deserving of playing time 15th and 16th players. The penchant for this blog to fall in love with these guys and project them to be so much more than they are(like rotation worthy players that should then cause Ainge to trade away much more talented and playing time worthy players) or they deserve is what I am talking about, rookie or no rookie.
Maybe clarifying that will cause your mind not to boggle so much 
I saw the same phenomenon during the 70's and 80's with Patriots back up QBs. Before Bledsoe came along the Patriot fan base seemed to be enamored with whoever was the back up QB at the time constantly calling for the benching of the starting QB, regardless of whether that back up QB had any talent whatsoever.
Well, that's the issue... you're comparing them to players that actually deserved playing time (particularly Randolph and Darko) against a rookie who clearly doesn't.
Maybe it would be best to compare him to Patrick O'Bryant reactions. 
Shav Randolph didn't deserve playing time and by the time he got here neither did Darko. Guess we will just have to agree to disagree there.
Darko would've been a starter on that team, he got injured and things spiraled down from there. At worst back-up center behind Garnett.
Randolph did deserve the playing time he got with our roster back then, and he got it... so not sure what the issue is there. The only real reason he didn't remain was because last year we were dumping salary and moving the team in a whole different direction. Had he remained, he probably would've managed to get quite a bit of action at the 5, but we had a bit of a logjam at the PF as it was, so we'd have to have time for them first...so his time would've been minimal.