Texas has the federal government to fall back on in case of, for example, natural disaster. The federal government doesn't have such a safety net; it must self-insure. On top of that, the federal government has to be prepared for contingencies such as war that do not really apply at the state level.
The period of time, one year, is arbitrary. Requiring a balanced yearly federal budget would be like requiring a balanced personal budget every two week pay period, even though my biggest expenses occur monthly.
What we really need is some way to balance the federal budget over a much longer period of time, a decade or two perhaps, spanning a full boom/bust cycle. This is, of course, much easier said than done.