It isn't like Apple and Google are not also trying to lock you into their platforms.
Google is a bit different, since they have a distributed platform that you can use on literally, any OS. They definitely want people on their platform, but so far they haven't taken any steps to 'lock' people in (I mean, they renewed their contract with Mozilla, they open-sourced Chromium/Chromium OS, Android, etc...).
I suspect most people are in Google's ecosystem simply because it's better. And until Google say, makes Chrome and Google services run only on Chromebooks and Motorola phones, I'd say they haven't behaved the same as Apple and Microsoft.
I know "competition is good", but microsoft isn't very good at competition.
Microsoft can't stop the success of other platforms as we've seen repeatedly in the 8000 years since that catchphrase hit the intertube forum messages. Interoperability will happen eventually regardless of whether MS initiates it or the EU demands it, because one day someone's going to be pissed off they're expected to "re-buy" half their apps and forget everything else just because they bought a new phone.
Google Chrome vs. Microsoft's IE6, Android vs WinMo 6/6.5, Gmail vs. 2004-2009 Hotmail. I'd rather put up with Google's decent-but-free alternatives than Microsoft's we-are-the-leader-so-we-will-stagnate-until-the-EU-demands-it-which-could-be-6-years-maybe-more.
Microsoft will push for better interoperability between the two OSes, however MS will notably utilize proprietary features (disk access protocols or some-such) and encourage handset manufacturers to utilize and rely on these proprietary interfaces.
What's the problem with this? More features are better, right?
Wrong. When it comes to Microsoft, they will happily and quickly change proprietary communications protocols and file formats so that competitors -- AHEM, partners -- cannot keep up with these changes. At some point in the future, MS will ignore requests for technical specifications on the changes made and the partner's features will languish into obsolescence.
Features built on top of this integration between the two OSes will be half-baked and second-rate compared to the native Windows Phone experience, and they will be frequently incomplete or unstable.
MS will be using this opportunity to influence the direction of Android (and its derivatives), and they will be pushing it directly into the ground. Integration between the two OSes will break and Android will be left out in the cold.