@lightningjynx

"Sure, you may get to lvl 80 quicker by going up in higher level zones, but if you are missing at least 5g per quest after the conversion ratio is it really worth it?"

This is, in my opinion, a common misunderstanding on two points. First, given that there are plentiful daily quests at level 80, there is no such thing as "missing the 5g per quest" by skipping lower level quests. Unless you are doing more than the 25 daily quests per day, you are missing zero income from the lower level quests because you can fully replace non-dailies with dailies.

And second, my point is based on what's referred to as "opportunity cost." If it takes you a week longer to hit 80 (based on the 20-35% decreased xp/hour), that's a week less of getting full gold on quests. If you play like me and do ~20 quests per day, that's 980 less gold (20 * 7g difference * 7 days) by the time the "save the zones" player catches up in level. The 980g is the opportunity cost of saving those zones. It could well be the case that this opportunity cost is a good investment if you play more than 25 quests per day and therefore need an additional stock of quests to augment the daily quests, but if not, it's most definitely less gold over the long run.

From a theoretical point of view, the best strategy choice is determined by which resource is more scarce for the player, time or available quests. Lol, I'm getting off topic now (warning! stop reading!!), but the best example in economics of this decision process might be the economics of forestry. There, you have a case where you have a regenerating resource (farmed trees, or equivalently, dailies) that may or may not offer adequate supply, and in the latter case, you can choose to draw from a finite and depletable resource base (old-growth forests, or non-daily quests). Interestingly, the result in forestry also varies by the interest rate, which in WoW terms could be roughly approximated by the marginal benefit of current gold consumption compared to future income potential and the discount rate on future WoW expenditures.