Perhaps, but the sad state of affairs that was the cancellation of Symbionic Titan probable had a lot more to do with the kind of show that it is rather than whether or not there were toys made to promote it.
While Princess Bubblegum and Princess Llana are two great characters, it’s not really fair to say that one should have succeed because the other did. They inhabit different worlds in different shows and nary the two shall meet.
Ultra, from Dan Meth's Meth Minute 39 series. A parody of Gem and described by Meth himself as: "a loving tribute to 1987, when cartoons were just badly animated toy commercials and women who rocked were outrageous."
Over at Fanboy.com they have a post that counts down some of the top (in their opinion) girl oriented cartoons of the 1980s, the supposed golden age for the genre.
The list includes the likes of:
She-Ra
Strawberry Shortcake
Punky Brewster
My Little Pony
Jem
Gummi Bears
Care Bears
While it is admirable that such a list be compiled, it does seem to miss the point when it comes to animation and who it is aimed at. Just because a show has a female lead does not automatically make it a ‘girly’ show. For examples, see Kim Possible and My Life as a Teenage Robot, two shows with very prominent female leads but far from girly (both contain numerous shots of people getting punched in the nose).
The same goes for the content, just because it isn’t all guns, lasers and fast cars does not mean that no boy is ever going to watch it. I got plenty of mileage out of both the Gummi Bears and Care Bears when I was young, and I certainly didn’t think they were aimed at girls in the slightest.
The post does kind of lament the decline of these kinds of shows, but that is not without reason. Firstly, the majority were created to sell toys, and you can’t really sell a girls toy without a girly show to go along with it. A fine example is My Little Pony, you might as well make that about as girly as they come.
Secondly, the rise of cable networks and the subsequent re-emergence of creator-driven programming eliminated toyetic shows like these almost overnight. This caused a bit of a shift in thinking wherein the shows became the source for toys and not the other way around. As a result, the nature of children’s broadcasting changed dramatically and the quality increased accordingly.
Nowadays you see shows that can appeal equally to everyone and that are of far superior quality to those we were accustomed to in the 80s. In retrospect, the ‘golden age’ was just a fad.