I suppose the following possibilities arise:
1. Remove 1 English team before semis
2. Give Barca a (theoretically) easy passage into the semi
3. Have a good TV game - Roma seeking revenge for last year.
4. Good result for UEFA whoever wins (3)
5. Give Chelsea a (theoretically) easy passage into the semis
6. If (5) comes off, remove one more English team, but...
7. Have guaranteed English presence (good for TV figures) in the final.
You could also add the thrills and spills of a Barca vs Man Utd semi (no offence intended, Roma fans - if I were a Man Utd fan I'd be a little worried by the tie).
Without being rude, I can't help wondering whether the cry of 'rigging it's a disgrace ' would have rung so loud from Merseyside had Liverpool drawn Schalke or if the bloke complaining had been allowed to place his bet at William Hill. In all of this, no-one seems to be noting that the complainant, rather than going to the press with his scoop about the rigging instead went to his local betting shop to try and pull one over on the bookies and only moaned when told that he couldn't do so...
Perhaps I'm just getting cynical...