Is a 1MB limit needed to "increase creativity"?

No.

One of the common last-resort objections to Bitcoin Cash's scaling plan by BTC supporters is that a 1MB limit is not just an unfortunate technological hinderance, it's actually beneficial in that it mandates engineers to be "more creative" in finding ways to increase Bitcoin's scalability. If Bitcoin can simply scale the blocksize, isn't that "taking the easy way out" & reducing the motivation for engineers to think innovatively & find other efficient ways to improve Bitcoin scaling?

It is true that imposing constraints increases human creativity. This is a known element of human psychology. For instance if given a blank piece of paper and asked to simply draw most people will sit in confusion feeling a total lack of ideas. However, if prompted to "draw a picture of a house" then suddenly they are full of inspiration & pen immediately goes to paper.

That said, there is no need to add artificial constraints for problems hard enough to already be constrained by reality.

If asked to climb Mt Everest, would anyone say "Please cut off my leg first so that I can be more creative in figuring out how to do it?"
Would any rocket engineers decide they must ONLY use wood (no metal) to build their Mars rocket in order to increase their creativity?
Does any music artist decide they can only use 2 notes to compose a #1 Billboard song?

When the problem itself is not trivial, there is absolutely no need to make it any more difficult than it already is - there's plenty of constraints imposed by available resources or physics to drive creativity in finding a solution.

Scaling Bitcoin to global reserve currency is already a monumentally difficult task. The Bitcoin Cash community is already under extreme constraints in terms of the available time, money, human capital, software, hardware & more (so of course we'd love it if you'd like to help out!). The difficulty of changing the opinion & financial habits of billions of people is more than enough to fill Bitcoiners lives with creativity-inducing constraints & obstacles.

The nonsensical belief that global adoption of Bitcoin is too easy & needs an arbitrary 1MB limit is of course the result of propaganda & needing to find excuses for failing ideas like the Lightning Network.

Note also that anyone who thinks it's the easy way out should simply try advocating to raise the 1MB BTC limit & discover for themselves whether it's a trivial task or not. There's plenty of problems with BTC to drive their creativity.