I do see your point, but I still can't agree to the idea of abandoning any continuation of the land before time even in case of some more good sequels.
There are still stories left to be told. While I admit that it is very unlikely that the glory of the earliest sequels will ever return I also see that in spite of some extreme shortcomings in some cases there was still a lot on the positive side in case of most sequels. Cut out the rainbowfaces (or their obvious departure), take a little more care about the colors and LBT 7 wouldn't have been too bad. LBT 8 was a good basic idea too. Take more care about the realism, at a little more depth to the character conflicts and developements and it would have been good. LBT 9 was simple but good. There were some plot holes (e.g. why couldn't Petrie fly just a little higher to tell their parents about were), but some nice music, some very emotional scenes, and scenes which reminded of earlier LBT movies in a positive way. LBT 10... well, it is the one of which I wish that it had never been made, but most of you disagree with me. There are emotional scenes and beautiful music to it.
My point is that LBT hasn't deteriorated beyond recognition and it need not do so even if the series is being continued. And if good sequels continue to be produced I suppose this would do more good on the economic sector than a high roman numeral would do bad.
Once the series is stopped the merchandize would cease soon anyway, so why not give it a try. With some enthusiasm, creativity, and sense for what made the early movies good the production team could still come up with something.
I don't think LBT should be abandoned lightly.
I hope my mind won't be changed by the TV series I haven't seen yet.