The Marvel Cinematic Universe is at a weird point right now, where a lot of the stars that made the meta-franchise so all-conquering are moving onto other things. Robert Downey Jr's almost certainly making his last appearance as Iron Man in the upcoming Captain America: Civil War, and the whole Avengers line-up is different after Age Of Ultron. There's no guarantee that Mark Ruffalo, Chris Evans or Hemsworth will stick around in their respective roles, either. More than anything, age is a factor: none of them are getting any younger, and signing them on for multiple films means that when they get to the end of their contracts they may very well be too old to convincingly play young, hot, super-people. As for Tom Holland? Once again, his youth is a total boon in the role of Spider-Man. You can make Spidey films with him in for years, along with all the requisite cameos in other Marvel films (in fact, he's rumoured to appear in Civil War). Perhaps this is the first Spidey who won't be recast and rebooted after three films.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/
