I honestly think that ogres and tauren should be classified as large. I seem to recall a Dev saying that in character the latter are some 12 feet tall and that their models have only been shrunk to keep them from getting stuck in doors.
I think you just answered your own question.
Large-sized creatures in Dungeons and Dragons (or any grid-based RPG for that matter) come with plenty of problems. Environments need to be accounted for them, because they take up an entire 10′ hallway. If they’re a melee combatant, they don’t play nice with other melee, often crowding their allies even in open locations. And like you said, even something as simple as squeezing through a 5′ doorway becomes a hassle.
Yes, there are abilities in D&D 4e that can turn you into a Large creature, but they are almost always higher-level Daily abilities that are temporary. The earliest is an obscure Wizard utility at Level 12, with everything else following being either capstone Paragon Path abilities or a feature of an Epic Destiny. Likewise, the earliest a Large-sized creature can be summoned are Level 9 Wizard and Druid dailies. Nothing of the sort can be done at Level 1.
Classifying Tauren and Ogres as Large-sized creatures would make sense given their in-lore and in-game sizes, but in my opinion, the problems outweigh the benefits. That being said, right now a racial Paragon Path for Arakkoa is being made to give them back their wings, so a racial Paragon Path for Tauren and Ogres to give them back their size wouldn’t be out of the question.
After I take another pass at the existing races and post the new ones, I’ll see what I can do!