It shouldn't. If smithing or enchanting are mandatory to play without frustration at high levels, then I've yet more reasons to say that the gameplay mechanics are deeply flawed. Also, I don't have this problem with daggers or swords when I do stealth kills. It's the 3X multiplier that is too low! If you don't take the perks, the sneak damage for all weapons is 2X.
Bows 2X > 3X
1H 2X > 5X
Daggers 2x > 15X
Something is not right.
Upgrading your weapons is something you have to do in most RPGs... I will agree that the upgrading system does have it's flaws (it should allow for NPC smiths to upgrade your weapons, up to some extent, for a fee) but still, it's not really hard to put a couple perks in smithing so that you can have decent upgraded weapons. Just getting the perk to upgrade magic items i enough, since for a non-enchanter the best weapons are some special artifacts.
Besides, there would be no point to add enchantment and smithing if you could beat everything with unupgraded tuff, would it?
Now, as for the sneak perks: true, 3x is much less than the x6 of 1-h and x15 of daggers, BUT:
It's infinitely easier to sneak attack as an archer than as a melee. It's also infinitely easier to hide afterwards.
As a sneak archer, you can sneak attack someone among a group of people very easily. As a melee, it's much more difficult for the others to not spot you.
As an archer, you can chain up to 3-4 sneak attacks on the same target before they find you. As a melee, you can at most do one attack.
Daggers have no reason of existance except from that x15 sneak bonus, as they are pathetic otherwise.
Archers get slow motion, which let them sneak kill a whole group of enemies before being found out. Melee have to react in real time...