Mattel was smart- they marketed through Facebook and Youtube. They also did the right thing for the fiction and didn't make "yet another" cartoon for girls of going to the salon and merely shopping for clothes. MLP G3.5 and Bratz seem regarded mostly as garbage thanks to that(not that G3.5 looking like a cross between marshmallows and Lovecraftian horrors helped any). MLP FIM also did well because it wasn't a watered down "fashion fame and boys" thing. MGA also seems to be going in this direction as the Bratzillaz webisodes have that same "Tex Avery mixed with Whitest Kids U Know" feel that MH and LITD have.
MH has slipped though. Some of the recent webisodes have felt bland, and the Abbey/Heath felt like on that was delayed as they sold wave 2 SO Cleo in it. II think dedicating webisode uplaod days to the toy commercials and We Stop Hate also bugged people. Their once a month schedule is also falling behind the once a week schedule of Bratzillaz and even Barbie is every 1-2 weeks. The scooter and mall episodes felt like a return to form but that new year's one felt a bit... out of place? I don't mind using them to sell the new toys, because cartoons based on toy lines exist to be disguised product ads, but some do it well, others seem more blatant. There are also the odd moments where some new doll or product gets 2 seconds of screen time, and I have to wonder if newer styles would sell better if they'd only change the animation models to let them wear new clothes. This is why people want the original signature dolls so much because that's what they wear 99% of the time.