Mobile gaming is an inherently different platform to consoles and PC, we are not going to see the same types of games that we would have seen on those platforms. For me, and most Sega fans that's not a good thing at all. I also, probably like many gamers, have little interest in phone games because it's rare for me to play them, let alone pay money for them.
I can see why this would be seen as a negative by most gamers.
As for Rome 2, maybe it's mostly the fans who got upset with that game? I don't read many/any reviews so I don't know how it fared with the press. General consensus amongst fans seems to be that it's the biggest misfire since Empire (possibly worse).
I excluded Alien because it probably got very positive press for being a good game. Did articles about this game also include negative points about Sega? Genuine question, as I said, I rarely read any gaming articles these days so wouldn't know. Having said that, Alien is probably the only game released last year from Sega I had interest in buying (Bayonetta 2 being a Nintendo game in my opinion) so I can't say I disagree with Sega's output being 'mostly mediocre' these days, or at least not appealing to me.