You're comparing apples to oranges. WebOS was closed source with limited hardware vendors. FireFox OS is open source, open to all hardware vendors.
Good platforms tend to do well in the marketplace because they attract investment from the outside world. Android is beating iOS because it's a better platform for vendors. FireFox OS is not only a better platform for vendors than iOS, it may turn out to be a better platform for devs than both iOS and Android.
Even if it the profit is big, it might not be big enough compared with whatever else they might producing instead.
When normal people buy a mobile, many choose a specific model, because:
- how it looks
- certain persons they know the same model
- there is a specific set of apps they want to have
- how the battery holds
- for whatever reason they want to have a contract and have a limited set to choose from, which fall anyway under the previous points
The question is how to bring these persons to buy a FirefoxOS mobile.
Sure a few geeks will buy them, but will it be enough quantity to keep the operators selling them?
It is great that Mozilla is fighting for openness, but in terms of what street joe and street jane want, I think it will join WebOS in a few months.
Given my experience in telecommunications I don't see how sales are going to push these devices out of the shop when users come asking for other OSs.