Dispensationalism is a fairly new phenomenon and totally changed the thrust and reading of the Bible...
It this is what constitutes a cult, then I don't see any point in applying the label, because the label is intended as a pejorative. Using your fairly benign definition, Catholics are well justified in calling most of the rest of us cultists, and then sticking us with defending ourselves against the negative connotations of the word.
Instead I would suggest demonstrating that dispensationalism is worthy of carrying the pejoratives associated with the word cult. Then if the shoe fits, don't acquit.
Alternatively we can decide that cults are the branch of Christianity that is the least Biblical, or that meets some other relevant objective or subjective standard. But just being new and saleable isn't a standard I'd want to bother with.
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass