Finding gear on your toons is a constant goal while leveling, and then becomes the primary target for the way to differentiate yourself from other players at 70.
Class dependency and spec choice will help determine what upgrade path is best, and many specific class sites, blogs, and forums will help with this (but please keep reading).
However a key point I have noticed in the change from pre-70 to 70 is the realisation that the upgrades, patches, and enchants for gear is critical in improving your gear.
I like to think about it like the player is taking responsibility for the condition of their character and the manner that character affects the world.
Spending the materials and time in getting it properly setup may be seen as a waste, as the gear might change; but that gear may also stay static for several weeks. Over those weeks you are reaping the reward of applying the enchant. I agree to a point that you should not waste enchant mats, but simple armour kit or enchant can help your team not suffer as much.
The effort to carry your character through an instance that has not applied some simple upgrades can be noticeable to the other players. And the good news is that these upgrades can also have a reverse bonus affect, they can increase your gear to a level well above basic performance. By enchanting and buffing your gear everyone wins.
Honestly there is no excuse when you have a 70, as money from daily quests will allow you to purchase most simple updates. The exception to this is Rep Reward upgrades which will be a while away for recent 80s, and most players can appreciate those being missing. The next time I see a toon with no enchants and no patches, I’ll be speaking out immediately.
Lastly as a rant on the side – Why then can my enchanter not be used to advantage on my other characters?
It is a totally broken aspect of the game, and while I suspect Blizzard will fix this eventually, I think the fix will only be in response to an external force (such as game feature comparisons). I don’t care if these were Bind to Account (BtA) so that only alts could use them; and imagine how cool it would be to scan the AH for Enchanting Kits the same way we can Armor Kits (Leatherworking), Scopes (Engineering), Spell Weave (Tailoring), Gems (Jewelcrafting) etc.
Please Blizzard, allow us to create Enchanting Kits, to swap between our characters.