Hi and welcome to the community. I feel I should apologize for my fellow community members who may have replied out of anger at feeling offended by your OP. Your opinion is your opinion and you are entitled to have it, same as anyone. For future reference, you may want to refrain from making general statements like "...how bad that game is," and instead state it for what it is: your opinion. For example: instead of saying, "...how bad that game is," you could have said, "...how bad I think that game is," where the "I think" translates into "in my opinion." Y'know?
On topic:
I was right behind you, thinking, "This guy seems to have at least an average understanding of what he's talking about," as I read your OP and your replies to others.
That is, until I read this:
To use your example of a player running along when you toss a well-timed grenade, "luck", as you put it, would still be as much of a factor to whether you scored that kill even without Sprint (or any other AA). If that targeted player simply stopped moving, it would have the same effect on that plan as if he had used Sprint to dash on by.
"Luck" has always, and will always play a very large role in the Halo games. Its effect on "tactical play" has been the same - consistently random - since H:CE. We can try to control our opponents position and direction with well-placed grenades, firing-lanes, and control of the right power weapons. We can try to plan our attacks all we want, but if our opponents have even one course of action that they can take to avoid falling victim, then it all comes down to luck whether or not they take that opportunity.
As for AA's being a "problem", I don't know what to say. I've never been a big fan of the name "Armor Abilities". I think they should have been called "'SPARTAN' Abilities" because, for example, Sprint and Evade aren't technically abilities made possible by the 'MJOLNIR' system, but are things all 'SPARTANs' can do, with or without 'MJOLNIR'.
There are only three AA's I've found to cause a problem between "balanced gameplay" and "fun utilities" from my perspective.
Active Camo
Armor Lock
Jetpack.
The first lets you hide in plain sight and makes me look at CoD campers with admiration (which is just wrong for me to do). The second makes you virtually invulnerable for five seconds and makes the multiplayer action grind to a halt too often for me to be cool with it (doesn't stop me from using it to survive nade-spamming, which I also find distasteful, and I found myself using it to survive my own team's haphazard nade-tossing more often than the opponents'). And the third has proven terrible to me for allowing players to exploit a map's architectural flaws and the oversights on boundaries, effectively ruining what little balance the multiplayer maps had in Reach.
Apologies to anyone who disagrees with me on any particular point. Twam bless you.