Interesting. I see your point with first alternate, but I am unsure why it is a bad thing for 1st alternates to be able to withdraw easily.
it's a good thing for the first alternate but a bad thing for the clarity of the Tour and rules. If you regularly look at the entry-lists like me, it really looks like a remanent joke seeing Roddick in the list and having to take him out just because he didn't bother writing a letter to the ATP. I hope he will do it in the off-season though. If they keep him in the rankings, they should also keep him in the anti-doping where-about procedures imo, and if he doesn't send his where-abouts, you should just take him out of the rankings and entry-lists.
For Roddick, I hope he'll stay in the rankings as he's got a nice series of weeks ranked in the top-50 and top-100. No reason not to prolong them IMO.
because he gave up, that's enough of a reason in my eyes. Hewitt, Ferrero and many other players made great efforts to prolong their "streaks" in the top-200 or top-100.
Ljubicic also was very high in the rankings when he retired but he properly wrote a letter.
As for Sampras, I always thought he was unsure whether or not he'd continue playing. He suspected 2002 USO was it, but if in doubt then you shouldn't really announce retirement, should you?
if you're not sure, you shouldn't announce it before your matches imo, because it puts all of your matches into drama, which of course is not good for opponents. I don't remember if Sampras announced it before or after his match though, I think he did it afterwards, which is more fair imo.
Clément only announced it after his final match in Wimbledon qualifyings.