If all of this is known by Bungie, they shouldn't devise an event reward system which penalizes you for those things.

The system doesn't aim to penalize for lag though. It's just an unavoidable part of the Crucible given the way the game was designed. While you may be 'penalized' for it, so too may your opponents, thereby leveling the playing field. Removing all lag/netcode/network problems would entail making an entirely new game, so this complaint is actually still just a general complaint about lag, which is fine but not at all specific to Trials.

I think there has to be a way to let everyone compete and get rewards fairly. All or nothing to get to Mercury is stupid.

I disagree with this opinion. All or nothing to get to Mercury is awesome, not stupid (in my opposing opinion). It gives great players something to show for and it gives less-than-great players something to strive for. There is no inherent reason that everything in Destiny must fall under the same "just put in a lot of grinding and you can have it too" category. Trials is the first event of its type (as in it's the first that isn't a simple grind to the end, but rather something contingent on natural skills, deep pvp experience, AND a bit of grinding).

So many people will never get there if only just because a few experiences in ToO will make them feel its impossible and they give up. That's lame.

I think that's totally fine. Not everyone should be able to get to Mercury.

Every other piece of content in the game has been much more accessible so far. If you grinded enough, you would get there.

Exactly, which is a great supporting point to my argument that Trials is a good event because of how unique and fresh it is. You're exactly right -- you can't simply grind enough to get there. And that's awesome.