yeah sadly, well then everything depends on some indie studios to deliver to the nice crowd. desura and matrixgames are also a nice example of some sites, which deliver some indie games, where the ladder got the ones with depth.
stardocks sins of a solar empire franchise is the best example, its a very good game, but it's a more casual game then galciv for example. both games are great on their own terms, where the one delivers some quicker action with some nice visuals, where the other one gives a plethora of depth and longterm enjoyment.
some more casual games can be fun if you don't have so much time or simply don't want to spend the next few horus or even days playing a game cause more of the indepth strategy games take a while. some casual games can be nice for inbetween. i personally see the problem in the difficulty of modern games. how many AAA are released which can be sad about that they have a good / decent AI and which are quite challenging to play in general? after seeing some reviews of for example assassins creed black flag it was obvious that this game for example has nice visuals and maybe even a nice storyline and a bunch of interesting features, but it being too easy to play through isn't really a good thing. some peoples i think are so oversaturated with easy-mode games which allow games like dark souls for example to florish. but it seems even dark souls 2 fell victim to the more casual crowd, after viewing some video reviews it seems that they made DS2 also easier.
maybe another reason why some games are rather light in features and challenge is because of a problematic learning curve which might put off a certain amount of consumers. games which are too hard or which rather have a more complex game mechanic have also the problem of being lower rated. how many times have i seen someone rating xy game bad just because he / she was too stupid to comprehend the game mechanics.
a good example of a VERY indepth 4x space game which is rather unknown and has a big learning curve (with a huge reward) is distant worlds. distant worlds is THE best 4x space game which you can buy for money at the moment, but sadly it is not so well known. it is also quite expensive when not on a release or holiday sale. it is expensive because duo to its steep learning curve, high amount of features & depth and rather having a nice 2D graphic instead of AAA 3D makes it sell less which in return the devs / publisher have to price it higher so that it become profitable.