I think that the current generation audience may be indifferent to the sahitya because (a) It is all "religious" in nature, so what difference does it make. (b) Most composers do not integrate the sahitya with the music. (c) Musicians do not communicate with the audience.
Speaking only for myself, I am training myself to pay attention to the meaning of the sahitya over the past few years, mainly due to the association with fellow rasikas here. The following is how I view the integration of sahitya with melody and rhythm. Even without understanding the meaning,
a) the alignment of words and stress points with the thala provides me one level of such integration.
b) The riding of the melody contours over the words provide the next level.
c) The third level of course is the understanding of the meaning and integrate the sahitya anubhava, raga anubhava and laya anubhava ( so to speak ). I agree with you that such an experience is quite fruitful to a rasika.
Having said that, in practical terms, Sanskrit, immensely fascinating it is, is not that easy to understand when a musician sings a sanskrit composition. It sounds nice from a) and b) point of view. That is what I tried to convey in my previous post that a lot of CM concert goers will be perfectly happy with a Sanskrit composition of yours in a secular theme since it provides them with enjoyment at a and b level. That is a way to get into the 'game'. Then you may get a subset of people who rise to your expectation of cultural sophistication to enjoy the composition at the level you expect.
Back to my own case, I have had a few cases of such integrated experience and the 'core' subject matter even in the religious context is not that religious at all. For example, I have read up on the meaning of Thyagaraja's song 'entani nE varNintunu Sabari bhAgyam' in Mukhari. There is no doubt about the religious context but I relate to it as an expression of fascination at the luck, blessedness and opportunity Sabari had in serving Rama. That emotion carried over the Mukhari bhava is an integrated experience for me. A lot of T's compositions provide for me such human context behind such religious themes.
Another clear example of relating to a sahityam with music is that viruththam I mentioned earlier. Since it was in a language I understood, no prior preparation was necessary. I have probably read the words of that before and probably have heard somebody recite it but it never meant anything. But when it was sung with music ( only melody in this case ), it just sunk in deep. The subject matter was about what kind of friendships and relationships one should develop. Somewhat religious but a lot of secular and human context can be attached to it.
The point of all this is, I consider myself a somewhat serious listener, probably in the 45 percentile of the concert going audience and I can deal with and prefer, fairly abstract concepts in the sahitya ( religious or secular ) if it is in a language I readily understand. The rest of it, I can enjoy for other aspects, 'a' and 'b' above, the non-meaning related integration of sahitya with melody and rhythm.
That is what you are probably dealing with in terms of the CM audience. Culturally sophisticated but not to the level you expect. I am sure there are numerous rasikas in that category but my guess is it is a smaller number. I would not necessarily classify the difficulties along the lines of the three reasons you provided. They are all true to some extent but if people do not understand the sahitya readily, where is the chance of going beyond 'a' and 'b' to that grand integrated experience you speak of?