I was thinking about this recently as well. I can't speak for a recording artist or the average music consumer, but I think the whole dynamics/loudness issue is blown out of proportion, or at least dramaticized by aspiring producers/mixers that heard an old school mixer complain about it once. Truth is a lot of the noobs in the music industry "protesting" about the lack of dynamics in modern music can't even properly identify when something is heavily compressed or not, as you can hear in their own music/mixes. My opinion is, a lot of the music I like (rap, pop, EDM) sounds good when it's loud and up front.. A lot of theses songs are meant to sound aggressive, which is often times achieved by putting many sounds right up front in the mix. There's a difference between being loud, and being squashed. There are plenty of commercial tracks out there that I think sound really good and aggressive and have ridiculously high RMS levels, but the engineers knew how to create perceived transients with various mixing techniques so it all worked out. When I listen to old songs, like Michael Jackson or funk or something like that, yeah the mixes sound nice, but I'm always telling myself "man that would sound good if the kick had some more oomph to it, or that drumkit was slamming harder," but that was not the style for that era and genre of music. Sure there might technically be more dynamics in the older songs, but who's to say that more dynamics is better? Some of my favorite songs have high RMS levels and I would not have it any other way. Now back in the day if you tried to push the compression on those songs the consumer might not have liked it, but that was in their time, this is our time, and things have changed. I would NOT want my tracks to sound like an 80s pop or funk song..I like bangin kicks, and hard hitting snares.
It is also my opinion that it doesn't matter how low in volume your track is at the production and mixing stage if it sounds good and balanced. You can immediately identify an amateur mixing job because everything will sound pretty flat, so no matter high you turn up the volume it's going to be a bad mix. But if a great mix has low RMS levels, as soon as it's played by someone (excluding the radio or club) they will at least give it a couple seconds and turn it up to hear it, and when they do, they will hear the great balance and depth youve created and continue listening. Now the reason the loudness wars began was because of the radio.. they played tracks at the same volume so naturally some masters they got were louder than others, and found that people perceived the songs that were louder on the radio to be better, so since the radio doesn't adjust the volume for each song, the mastering engineers started squeezing the juice out of these things to get that edge on the radio. Same thing with the club. I'm not a DJ, but often times is seems they do not adjust the level of each song (unless it was drastic), so you'd want to make sure it is pumping so people perceived it as a banger. I might be off on the club reference, but I have been to many underground shows and so many people looked lame on stage because their backing tracks had no energy.. people need to hear that bass hittin and snare slamming for hip hop stuff. I've never seen a DJ at an underground show turn up someones beat because the vocals were too loud compared to it unless someone went up to him and asked him specifically to do so.
Overall my sentiment is, don't worry about it on the production or mixing end, unless you're acting as the mastering engineer as well, and the song is going to be played on radio and the club, in which case you should spend some time learning to get it to an acceptable level without squashing it. If the artist who buys your beat is going to have it mixed and mastered by someone else, it's their responsibility to get to a proper level. My tracks usually end up around -12db RMS, which is a nice middle ground in the mix stage, but most stuff I hear on the radio is around -9db RMS. When I play my mixed beats for clients or other producers, I've never heard that my RMS is too low, and I get a lot of compliments on my mixing.
One other thing to look into is, if you're going to be posting something on Youtube or Itunes, do some research about the their RMS level limits/algorithms; both of those sites will not allow RMS levels past a certain point, and will turn your music down for you when it coverts it, so if you mix the final track too loud, Youtube or itunes may turn it down via compression, and it could mess with your mix. Interesting stuff.