Clients are not reliable (Hence Ecosystem score is low)
This is exactly what I was saying regarding clients around a month back in my post :
For example , someone asks if Instagram is available in WP , I would simply say "NO"
After that , I get replies saying "Hey , don't make false comments , WP has instagram client(s) , Why you said no when he asked about instagram ?"
Clients are pain in the *** .These clients are always second class apps , Suddenly they break , they may not not work , Sometimes original app (non-client) app may feel bad compared to clients but these apps always work because they are original apps unlike clients.
Lets say that a reviewer recommended WP , he/she who is new to WP realizes Instagram client has broke or some features are missing or Google apps are missing , What will happen ? It will leave a negative impression just in few minutes.
You might have seen Instagram's article.
Giving Eco system as 5 = Not much fair but It should get 6-7 (but not more than that , that's the maximum it deserves in my honest opinion)
My experience with WP8 was the worst but that doesn't mean I hate it or biased against.WP8 may work for others but for me, clients never "appeal" as much as the official apps.
Note : When I use the word "client" , It means "3rd party client" , "original app" means official app