I agree if they cannot get original stars to do the sequels, they shouldn't make them then.
When they do a movie, they should find out if the original stars will do the sequels if they make them. I have been disappointed at sequels that didn't have the original stars in it so I won't even watch them anymore.
What would Back to the Future be like without Michael J. Fox and Christopher Lloyd?
Indiana Jones without Harrison Ford?
If I know original stars are not in the sequels, I do without seeing them.
Another thing that really frosts my cookies is when they make movies out of old tv shows and ruin them.
Case in point, Starsky and Hutch. It was a great tv show and they ruined it by basically making it a comedy.