Super Reflexes was changed for Sentinel to have the option of Master Brawler instead of Practiced Brawler, which gives you mez protection passively and can be activated to gain an absorb shield. This is a lot better design than having to click Practiced Brawler every two minutes to keep your mez protection, since it's an active ability that you have to use reactively. That means that it adds more interesting gameplay to Super Reflexes characters, which normally do nothing but keep their toggles on and maintain Practiced Brawler; it even scales the absorb amount with your missing health to reward good timing. I don't see why this should be exclusive to Sentinels; Super Reflexes already has fairly harsh downsides(no healing/recovery, no psionic mitigation, no debuffs or damage potential) so I don't see the harm in giving it a little boost.
Speaking of downsides, the Sentinel version of Super Reflexes also has a little bit of psionic defense and recovery added. I don't think it's necessary to add these to the other archetypes, but it would be nice to lower the investment needed to protect yourself from psionic attacks, as well as bring Super Reflexes on par with other defense sets which offer endurance recovery.