I'm certainly against safe seats, but this could be fixed very easily by having open primaries. If you live in a (for example) safe labour area, you could then at least decide which person within the labour party represents you area, and vote them out if you wish.
I'm also not arguing that the conservatives deserved a majority this time, clearly they didn't (and nether did labour in 2005 for that matter, they only got 36% of the vote). A hung parliament is probably the correct outcome this time.
PR results in coalitions. Coalitions give:
1) Too much say to smaller parties
2) Too many decisions made behind closed doors
Now, imagine if we had this same outcome in seats terms with PR. This is what would be happening:
A party with ~45% of the vote is being blackmailed by a party with 10%, and extracting demands and cabinet seats. This would be quite wrong. The views of the 10% would be vastly overrepresented and the ~45% under-represented.
Plus everything would be happening behind closed doors.
This would clearly be quite wrong, and is what I am arguing against.