I always wondered why don't we have just developer level. That is for those with say 5-7 years of experience. That are skilled enough to do their bit on their own, but might not yet fully see the big picture on whole application scale for whole thing...

Straight from junior to senior just feels weird jump. Junior and Senior sound like adjectives to me. Qualifiers. And there should be some middle point in between where bulk of the workforce doing the actual job should be.