She said that she often found herself putting on this voice as part of some sort of defence. I do think she's grown a lot since then in terms of verbalising her thoughts and generally having the confidence to actually say what she wants, but I do agree that there was an element of 'dumbing down' a bit at the start. Not entirely surprising considering the latest pop crop were pretty girl-next-door or sex kitten types (Britney, Christina, Beyonce, Rihanna, Katy etc.). If she'd burst onto the scene as a takes-no-bullshit-head-bitch-in-charge meets overtly-passionate-artiste woman to the degree she is now, I doubt it would have happened so smoothly. She had to earn the right to get away with that, much like Madonna did.
With Rihanna, I think it was more down to age/maturity. Although similar age to Gaga, she's much younger mentally (or rather, Gaga is an old soul trapped in a 25 year old body). Although of course she's exploring her strength/sexuality/general place in the world, I think Gaga's outlandishness has encouraged Rihanna('s team) to follow suit. I don't know if I buy that she's all out-the-box-controversial, but if it's how she wants to express herself - by all means.
Anyways, I've said it before, but it's astounding how good her back catalog is already - only 3 years in - let alone what it will be in the future. The way she's going, she'll pull a Madonna and genuinely have a massive (probably 2 disc) greatest hits with each track being solid pop gold, and absolutely no filler-hits.