Forms, whether you call them kata, poomsae, hyung, tuls, or whatever other words for forms exist in the world of martial arts, are meant to teach the technique. Much as the English language has various structures that you learn in school or as math has formulas, if you learn those structures or formulas but never write or do any math outside of schoolwork, then you have only part of the lesson.
Back when Maryland's sales tax was 5%, figuring the tax on an item was very easy. But I saw plenty of people who had taken college level math and had degrees that required advanced math who needed a calculator to figure out tax on an item costing 9.99.
Likewise, if you learn only kata, two man or not, and never spar, you do not have a solid basis for unscripted real-time self defense. Kata was never meant to be taught as an end unto itself.
Daniel