Everyone complains about how tier1 masses are way too important in Warcraft3; you simply cannot play a game without having at least an initial phase of tier1 massing. I've come to the conclusion that the excessive importance of tier1 in Warcraft (War3) isn't so much because of Creeps and Upkeep (although those are significant), but mainly because of the difficulty to defend a rush and the emphasis on neutral buildings.
The main thing that makes rushing way too hard to defend is the terrain of most War3 maps. Imagine playing Starcraft (SC) on Gnoll Wood, Dark Forest, or Battleground. There are no ramps, no real choke points, and expansions would be virtually undefendable without Town Portal. It would be a tier1-fest : zerglings and hydras would fight with medarines and zeal/goons. You simply couldn't tech because you'd be overrun.The reason teching was so well balanced against rushing and expanding in Starcraft was because you could cheaply defend against the biggest early-game rushes just by placing a few buildings the right way. In War3, if you want to stand a chance against a tier1 rush, you need to spend a ton of resources on towers. (and even then, Defend can own your ass) Once you've established your defenses, you don't even have enough money left to really tech.
Now what makes this much worse is that many "techs" are more accessible to the rusher rather than the techer. The importance of Goblin Merchants, Goblin Labs, and Mercenary Camps turns the traditional teching/rushing balance on its head. The techer does not have enough forces to assault these usually heavily Creep-defended buildings, so he must do without Zepplins, Reveals, Sappers, Wands of Negation, and Troll Priests. It is, perversely, the rusher who gets access to these valuable technologies. While the techer has to spend gold and lumber at each turn to research Hippogriff Mounting, Bear Form, Chimera Breath, etc., the rusher attacks Creeps at neutral buildings and immediately gains the ability to buy Wands of Negation, Scrolls of Healing, Goblin Sappers, and all the Mercenaries at the camps.Because of these two things, teching is just not beneficial enough. (you may have fast Spellcasters, but my tier1 horde cleared all the Merchants and I have several WoNs) The fact that you can't Creep as well while teching just adds insult to injury.
IMHO, the imbalance between tier1 massing and fast-teching can only be fixed in an expansion, by giving players tech options that are riskier but more powerful. SC (especially Broodwar) had certain techs that could kill you outright if you weren't prepared, but were easily countered if you were. Without detection, a few Dark Templar or Lurkers could decimate your entire economy. Fail to build enough Dragoons, and a fast Mutalisk rush could take you right out of the game. Most of the tech in Warcraft 3 shares neither the extreme power nor the extreme vulnerability of SC tech. Getting Knights instead of Footmen is just a moderate improvement to the power of your melee line. Bloodlust is only a 40% buff to the units it's casted on. The closest thing to SC-like tech would be the Steam Tank, but those are far too slow to get compared to stuff like Reavers and Dark Templar.Even with tech that is just as powerful and risky as SC tech, War3 wouldn't have as good of a rush-vs-tech dynamic as SC, because of the two reasons I mentioned above. However, it would certainly be a lot better than it is now.