Apparently what rerolling initiative means to people varies a bit. For my 3.5 group it was d20-style initiative (i.e. no speed factors, etc.) that gets rerolled each round. The unpredictability that brought to each round was incredibly enjoyable, but the rolling itself was cumbersome. We ended up using a lightweight initiative and condition tracker that rolled initiative for every combatant each round with a single click. Of course, the program rolled for the first round as well so physically rolling initiative stopped being a thing for us, which was a bit unfortunate. We decided that was a trade-off worth making and never looked back.
This did not work well at all in 4e because power durations tended to be both short and their effectiveness dependent on exactly when a creature's turn started or ended. So while in 3.5 the balance effects of rerolling initiative tended to feel like "rounding errors" that averaged out, in 4e the assumptions made when designing many powers in the first place were grossly violated.
Although I didn't play 2e, my experience with similar systems is that the book-keeping (even with some external aid) tends to outweigh the dynamism unless everything else is kept extremely lightweight. YMMV.
I voted for optional rule, and hope the final form of 5e works well with my preferred form of initiative rerolling.
This did not work well at all in 4e because power durations tended to be both short and their effectiveness dependent on exactly when a creature's turn started or ended. So while in 3.5 the balance effects of rerolling initiative tended to feel like "rounding errors" that averaged out, in 4e the assumptions made when designing many powers in the first place were grossly violated.
Although I didn't play 2e, my experience with similar systems is that the book-keeping (even with some external aid) tends to outweigh the dynamism unless everything else is kept extremely lightweight. YMMV.
I voted for optional rule, and hope the final form of 5e works well with my preferred form of initiative rerolling.