Are that many people really choosing devices because of ecosystems? At least for myself, I can't say I'm immersed into one. I'm using bits and pieces from all of them. Most people I know are too. Cherry picking the devices they think are the best for them
I think there are a lot of people that could benefit greatly from having a more integrated "ecosystem" experience, but most people don't realize it is possible yet. Mobile is still fairly new and people are just happy to have some of these devices. However, the reality is that people often find these devices to be more effort to maintain, update, and keep synced than they are willing to spend time on. As people become aware that in a good ecosystem all of their devices can work together almost seamlessly, run the same apps, and sync pictures/music/etc automatically I believe they will begin to consider those advantages in their purchasing decisions.
Agree. Locking yourself to one ecosystem is a huge mistake. It's much better to pick and choose the best option for the things you actually need. A big disadvantage of Windows Phone is that it ties you to Microsoft's services (OK, I know you can use others, but e.g. Dropbox can never integrate as well as SkyDrive). I'm not saying Microsoft's services are bad, but who knows if they will be competitive in the future. And you may some day want the choice to go with devices from other vendors.
Those examples don't make much sense. You are basically saying that people shouldn't take advantage of the benefits of ecosystems (specifically Microsoft) because they might lose those benefits some day if they switch to a non-ecosystem alternative. As if never having those benefits (even while all other functionality was similar) is somehow better.
I agree that "locking" yourself into an ecosystem (or proprietary format) is a mistake, but that doesn't mean that there aren't good reasons to align with technology that uses a single ecosystem as long as that ecosystem isn't cut off from other options. An "ecosystem" doesn't necessarily lock you in to anything provided it can be accessed from the outside. It just provides a more consistent and better synchronized experience. Apple's ecosystem absolutely attempts to lock in their users with everything from lightning connectors to proprietary protocols/formats and I avoid Apple products for this reason (although I believe they make good products). However, the Microsoft ecosystem is far more open than most these days. For example, OneDrive, Office, Xbox SmartGlass can be accessed from nearly any competing device. You don't see that very often with Apple and Google is being a bit selective with their "openness" these days too.
... But the strategies by Google, Apple and MS are to keep users in their fenced gardens ...
That is certainly true of Apple and to some extent Google, but MS has been doing almost the opposite. Out of those three big tech companies, MS is the only one that is embracing open standards (like Miracast instead of AirPlay/ChromeCast) and making their services available on nearly all competing platforms. I'm very thankful for that.