A couple of those aren't really sequels - mainly Atlantis and Tarzan and Jane.
Tarzan and Jane is actually a compilation of three episodes of The Legend of Tarzan with ten minutes of added animation and a couple of new songs thrown in. As for Atlantis 2 - it's actually a compilation of the first three episodes of the canceled Team Atlantis series that was being produced by Greg Weisman of Gargoyles fame (one arc of the series even would have had the Atlantis team finding Demona).
As for Lilo and Stitch 2 (called Stitch: The Movie) - this sequel was already in production before the first film had even been completed. The movie will set up the Lilo and Stitch series (called Stitch: The Series) and will follow Jumba's other 625 expiraments landing on Hawaii and having to adopt to the island - much like Stitch did. Unlike their previous sequels though - this one still had a lot of the original staff involved and all of the major voices will be back for both the movie and series.
As for the rest of them - all I can say is UGH! Oh well, I guess we should be thankful that they aren't still pursuing the Snow White DTV sequel.
"Never give in--never, never, never, never, in nothing great or small, large or petty, never give in except to convictions of honour and good sense. Never yield to force; never yield to the apparently overwhelming might of the enemy."
- Prime Minister Winston Churchill
"Si vis pacem, para bellum."