Eidos did this with Invisible war, they wanted a more accessible console friendly version of deus ex (dumbed down for ritalin popping xbox retards) because it did not sell all that well. Even though it was well received by critics and hardcore gamers.
Now this was at a time where the "casual" gamer did not exist, what this potentially means for the sequel
is frightening.
Another example might be Sands of time and its sequel Warrior Within.

What is really irritating is that the original game was not difficult or inaccessible at all with the sole exception of the last bossfight.
And that one was only hard because you had to memorize certain patterns, which admittedly was beyond annoying.