Internal studios or lack-of is not so much a problem if they could make up for it elsewhere. The problem is what the more recent pipeline of external content looked like.
I mean, we know that they have around 8-10 unannounced external developer games (excluding Forza, Halo, Gears ) in development right now.
If 5-6 of those unannounced games are AAA, then the lack of studios ain't really an issue. But as we've seen 2 years ago with ReCore, it leaves one with a feeling of dissatisfaction that a major reveal from that E3 turns out to be a lower budget endeavor.
Part of the expectation is seeing where MS goes with those Global Publishing games.
This strategy clearly hasn't been working for Microsoft, not in the past and certainly not now. Relying on external developers just creates too much uncertainty and confusion and Microsoft look like fools getting in their own way.
They had a great relationship with Bioware and let EA just swoop in and buy them out when there's no reason they couldn't have done that and maintained exclusivity on some amazing RPG games.
They had the father of Final Fantasy on board in the 360 era, and rather than to continue building on that relationship, they let that just go completely once Lost Odyssey didn't do gangbusters. If they hadn't been so shortsighted, they could have owned Mistwalker and not had to worry about JRPG exclusives, they would have been making their own and building a more diverse fanbase, and they wouldn't have had to suck up to SE to get Final Fantasy on Xbox.
Recently, Insomniac made a great game in Sunset Overdrive and Sony scooped them up to work on the Spider-Man IP. I can't help but feel that they saw the quality of SO and decided to bring them back into the fold whilst MS just scratched their heads and wondered why it didn't sell 10 million and if they should bother greenlighting a sequel.
Even when it comes to their own studios, Microsoft just can't seem to stop getting out their own way. Bungie were super successful with Halo, and probably would have been retainable if they'd just let them put that IP on ice for a while or if they created 343i for Halo and let Bungie carry on with their ideas, they sure had earned that level of trust. Even if some members of Bungie refused to stay, the studio would have still been in their possession and probably more would stay than stayed to start 343i.
I could probably think of more examples but the point I'm trying to make is this: the alternative strategy Microsoft has tried to employ simply doesn't work, and even if it did, both Sony and Nintendo have found and are finding huge amounts of success in investing heavily in both first and third party games. There's no reason we can't demand the same from Microsoft to get us invested in their ecosystem.