huh? you could only turn in like 2 quests of cloth(It had a cap). Back in WOTLK you had to faction change for it. I was one of the first people to get it. Took round 300-600hrs. You basically had to do every quest available plus Lunar festival. It took fucking forever. It's so easy to get it now. Rokay you get it now?
Technically, it depended on wether you had an old toon that had done a lot of Quests before spill-over Rep worked or not, on wether you did a year's worth of World Events or not, and on wether you were Horde or Alliance (Horde had the Chen Quests Rivfader fondly remembers ;P and the Gnomeregan pre-event - unlike the Echo Isle event - didn't give you Rep. If the later had, Ambassador on a Human might have just been possible in one year with better planning).
The issue was that before the Tabard system, the number of Quests was limited and hence the amount of Rep you could get was limited, meaning that the lower the level of a toon, the more content you would need to have cleared.
In practical terms, this meant that if a Human did all Quests and Events of a year, at 19 it wasn't possible yet at 20 it was, though this meant e.g getting all the Elders and Drop-Quests in the game; with other Alliance races & less Elders I got the title around level 23. In all cases it was Gnomeregan Rep which was the issue (and why the prevent not getting you any Rep - at least till teh costume reward - was so annoying).
You could get acces to more Quests- and hence more Rep rewards - by buying additional game content in the form of Faction changing. If you did all Ally quests at 18, you could get Ambassador as Hordie by doing only a couple of zones, which is why I tried it again on a level 10 Human Twink some time before the Shattering.
With all Ally Quests available done (though not fully all Events, as e.g. getting all Elders on a 19 was work enough, though admittedly my opposition to baby-sitting obviously did play a role) and the Horde Quests (except the Chen cases) I missed a couple of hundreds on Trolls and about 600 on Belfs if memory serves right when the Shattering happened. Yawning through the new Troll Quests and killing stuff in RFC because Silvermoon nowadys is greatly concerned with happenings therein (at least if you wear their ads; otherwise they don't give a damn) got me the Title.
Note that this also illustartes one of the reasons why at least on some servers 'Ambassador' on a low-level toon had 'meaning': it showed you had pretty much done most if not all the content available, and hence people would ask you advice on things.
Bottom line is that the Ambassador Title already was a bit 'iffy' once the unlimited Runecloth turn-ins became available to a toon (which had their purpose when introduced but were superfluous once spill-over Rep and other schemes appeared) , and the new Tabard system made it a lot easier to get the Title without a need to see a lot of the content, and the fact that the Tabards make no difference whatsoever on wether you're getting boosted or not has driven the final nail into the coffin - which is a pitty, there already were so few non-babysitting Titles available as it stood.