I've been wondering lately why Henry chose to seize the crown for his own rather than be happy with Richard II's abdication. He seems to have gained very little for the price of being called usurper; having Parliament declare him Lord Protector or Regent for Richard's most legitimate heir, Edmund Mortimer, age 7, seems just as easy, just as good a return, and lower risk. He gets real power for a decade and can marry his daughter Philippa to the King, then retire to be merely the Duke of Lancaster, richest man in England and the King's father-in-law.
The obvious stumbling block is the young King's uncle, Sir Edmund Mortimer, who could conceivably lay a better claim to being Regent than Henry. However, Henry is a Duke, very rich, and has an army, while Sir Edmund is a landless knight (a bit hyperbolic, I admit, but the point is clear). Further, Sir Edmund seems to me to have had little personal ambition and to have been a reasonable man; a deal seems quite possible, perhaps naming him Duke of Ulster, or Lord Constable, or both.
It's true that England dislikes regencies and minor Kings, having had bad luck with them, but surely it likes an usurper even less.
So what am I overlooking that makes this a bad plan? And if it is indeed a reasonable plan, what obvious effects do other people see coming from it?