Trust me, I'm not a troll, I'm just a big doctor who fan.
For the record, I love the classic series, I love Collin Bakers doctor, Patrick Troughtan and the Cybermen are awesome.
But the main problem with some of these old doctors coming back is that we know what they looked like just before they "died", so them coming back looking older then they were in their "deaths" would screw up the continuity. Although this time crash aging excuse is a valid one, personally I don't really like it.
And besides, despite out opinions, it looks unlikely it will happen. Although I am dying to see McGann back, I'm starting to doubt it ill happen, despite Eccleston confirming that he won't take part. Despite any of out opinions, it looks lie we're just having a Smith Tennant team up. Now personally I'm fine with that.