Yes, I think this is the crux of the issue:
Attractions should be able to self-support whether an IP is linked or not.
Regardless of whether the IP is popular, if an attraction is rubbish, it's rubbish. Stitch sums this up: a well liked, fairly popular IP, albeit not in the princess frenzy league, but certainly not disliked, yet the attraction is a complete flop. There is little to no logical story line and the audience are less than engaged in the attraction.
If an attraction is well designed, has a coherently thought through story, and is engaging with the audience it will be popular whether linked to an IP or not.
Splash is a good example of this, a lesser known, certainly not a highly popular IP, but extremely popular and well loved attraction done right.
Let's face it, Song of the South is hardly driving the popularity of the attraction, nor do many people get off the ride, rush to the gift shop and buy the DVD.
The main purpose of the attraction has to be entertaining guests not selling merchandise.
I think everyone agrees that the IP linked attractions are here to stay, I just hope that they keep in mind that if the attraction is not self supporting they will end up with a stitch not a splash.