Even with L-cancelling, it is still possible to time a grab well enough to stop your opponent in his tracks before he grabs you or does something else right after landing. However chances are that if you're in a situation like that, you shouldn't have been shielding for so long and should try to better space yourself away from the opponent (wavedash OoS, for example). I still agree however that L-cancelling doesn't require any skill to use and that there is no valid reason not to use it. Like many, I would much prefer that landing lag on most aerials gets decreased.
Like Eternal said, Brawl may look like it's more focused around mindgames and making good reads, but so is Melee. The only difference being that Melee has a wider plethora of ATs that enhance tactical play whereas Brawl's is more bare-bones and raw. And I guaranty you that if you just rush and attack relying on tech skill, you won't get anywhere. Powershield, crouch-cancelling, heck, even sidestepping, are good defensive options often used to punish a reckless opponent.
I do not want this game to become Brawl 2.0, nor Melee 2.0 for that matter. Like every previous entry in the franchise, it should feel completely unique, with only the simple stuff remaining the same, like rolling and sidestep.