I have quite serious problems with Pirelli, namely their refusal to push back proactively against FIA decisions that they themselves seem to think are bad (instead of waiting for the regulations' inevitable failure), their inability to make a tyre that is consistently safe when used reasonably (as recently as Russia, there were tyres suddenly going to the canvas after 8 laps in practise a la Michelin at Indy 2005 - luckily for them, they didn't recur in qualifying or the race) and their increasingly dodgy excuses when things go wrong. None of these are behaviours I expect from a tyre manufacturer, and none of these can be blamed on other parties.
The lack of testing is largely Pirelli's fault, for breaching the test regulations with Mercedes in 2013 and helping them get the domination they currently have. The teams knew then exactly how far they couldn't trust their tyre supplier, and both sides have paid for it ever since.
I'm not sure Michelin's technical changes would necessarily have been better for F1, but they displayed a far better attitude to racing, which would have been refreshing.
Really, though, this was decided by Pirelli willing to pay Bernie more for advertising hoardings than Michelin - which contravenes the Nice Agreement, which requires the FIA to be the sole arbitrator of such decisions. The moment the FIA said that the choice between Pirelli and Michelin was "subject to Bernie" two months ago, I knew this would happen. The EU will be furious, and that's a heavy price for F1 (literally and figuratively) to pay for Pirelli liking Bernie's advertising spots.