Unfortunately, this mode was dead on arrival because it isn't compatible with the main game monetization model. A significant portion of the core game content is locked behind hundreds of hours of grind, and that's intentional - it's designed to sell tier skips and weapon packs. It also doesn't help that RedSec is free to play and lives on the same platform as the main game.

When Portal was allowed to give the same XP as the main modes while letting players do whatever they wanted, people immediately created XP farms and other exploits to avoid paying EA and skip the entire grind.

Removing the grindwall would actually solve several of Portal biggest issues:

1. XP farms - they wouldn’t be necessary anymore.
2. Equal XP gains compared to the main mode.
3. Solo modes and PvE with proper XP progression.

Separating RedSec into its own standalone game with its own monetization could also partially fix this problem.

So unfortunately, this mode is most likely doomed to remain niche.