Ish. Sort of.
If you want to participate in the Android ecosystem - which is very much Google's baby - then you have to toe the line and follow the device compliance specifications. And, yes, pay Google for that. The reason for the compatibility testing, asides getting Google a little extra pocket change to swill around, is so that the Marketplace app knows what apps your device can support. It also helps somewhat with this fragmentation thing that everyone keeps talking about but I've seen precious little of amongst officially supported devices. I'm not sure how well, therefore, throwing the Marketplace open to every two-bit manufacturer and their dog like that would work. Would it have to run a benchmark on your machine when you download it? What happens if a background process slurps up resources, making the Market app think your 1.4ghz Cortex A-something has all the poke of an 800mhz ARM11? Not to mention some of the funkier hardware configs that could play havoc with apps that use the NDK
Most importantly, would it be usable by the mythical Joe Sixpack without having to learn about "megawhatsits" and "gigathingies", "ARM whatevers" and "Snapdragons" (aren't they a type of flowering plant, do they bite and can they breathe fire, etc, etc)? It'd certainly be amusing to get the "full Android experience" on a homebrew Beagleboard with an old laptop screen duct-taped on and a 12v sealed lead acid battery/housebrick in a caddy round back, but perhaps wishful thinking given the target market of.. well.. everyone including people who aren't geeks.
However if you're a company that wants to roll your own, build your own ecosystem and get a shiny product to market in a reasonable timeframe, Android is a rather good base upon which to build. Just ask Amazon, or Barnes & Noble.