So you prefer a weaker execution barrier? L-cancelling and wavedashing aren't the most important aspects of Project M. You could get pretty far without mastering either. If one isn't invested in winning major tournaments or being among the best at their character(s) then one doesn't need to stress Project M AT's. I don't wavedash much or L-cancel, and the game is still enjoyable at my level. Project M and Melee's AT's should not deter low and mid-level players from playing the game. Regarding infinites, could you give me a few examples of infinites in Project M? I don't recall seeing or experiencing any.
In life, I'd generally argue that quality > quantity. Character rosters is one of the areas where that line of thought holds. While Smash 4 has 10 more characters. Project M allows one to choose a minimum of 38/41 and succeed at a high level. I've heard that Jigglypuff, Olimar, and Ice Climbers need some serious work, but other than them I haven't heard major complaints about viability. Contrarily, Smash 4 cannot match that percentage of viable characters and may not even be able to match that total amount. The revised edge mechanics take away edgehogging, but is that really a good thing? Believe it or not, edgehogging is a significant risk. If you mess up or mistime your edgehog, you'll die. There seems to be an understanding that blast zones are farther out in Smash 4, so even if you go offstage, you might not kill the opponent since recoveries are so strong or automatic for many characters. Contrast that with Project M where characters living to 200+% isn't a common occurrence especially when playing on the great selection of small stages like Yoshi's Story, WarioWare, Green Hill Zone, or Fountain of Dreams. Furthermore, recoveries were toned down in 3.5 and there are edgeguarding options that aren't possible in Smash 4.
I apologize for my poor wording, the lack of infinites is an appealing trait PM and Smash4 share.
I've always hated edgehogging, so regardless of its risks or other properties, I see its removal as a benefit, and enjoy the new stage-spiking and other resultant offstage play that results from the rework. Those strong recoveries work both ways, making my offstage play safer. And personally, I liked having the strong recoveries of 3.02PM, as it further differentiated it from the "you're offstage and basically dead" aspect of Melee I don't care for.
And again, I don't argue that there's a lot to like about all of the games at all levels of play. But for me personally, I feel like I can play at a higher level in Smash4 on a larger variety of characters. I still enjoy PM, and Melee, and 64, but if I had to pick one to further my career in (or start my career in, as the case would rather be), I'd pick Smash 4, since it presents the lowest barrier to entry. I'm at the top of my friend circle in at least all but Melee (maybe PM now since another friend has been practicing it more), but the knowledge of what I can't currently do and would need to do consistently to be a valid competitive threat in the others is just not appealing to me. Perhaps if I placed greater stock in (or was better at) advanced techniques and quick gameplay and movement options I would feel otherwise, but none of PM's offerings (besides Roy, Mewtwo for now, and the music customization) really draw me to it over Smash4.
In short, I prefer Smash4 because it's easier to play, and by extension, I'm better at it, and many of PM/Melee's selling points don't appeal strongly to me. And if I'm to compete, I would like to at least stand a chance to recoup the entry costs, so I would indeed rather be a strong competitor. I can play and have fun with friends for free, after all.