It's a little late to get Richard back, isn't it, Hotspur?

I’ve only read the first act of Henry IV, and already there is so much to discuss. I could write an essay on the topics brought up in this act, but for here I need to post about the complete irony of how some of the characters feel in bringing Henry IV up as king, particularly Hotspur.

In the third scene of act one, Hotspur is going on a rampage about the king and his regrets about killing off Richard II. Around line 155 and following, Hotspur gives a mini speech about the betrayal of King Henry IV:

“…But shall it be that you that set the crown / Upon the head of this forgetful man, … / shall it be / That you a world of curses undergo, / Being the agents or base second means, / The cords, the ladder, or the hangman, rather?” (158-164)

Remember that Hotspur is actually Henry Percy, talking with Northumberland about this. These two men are key characters that helped King Henry IV (known in Richard II as Bolingbroke) get to the position in which he sits now. I find this part fair and understandable with how Hotspur feels: it does seem that after Bolingbroke came into power and became King Henry IV, he has forgotten who his allies were. Later, however, he compares Richard to a “sweet, lovely rose” (173) and Henry as a “canker” (174). I just want to say, ‘you put him there!’ How is now Richard a rose, when in the previous play Hotspur helped in getting Richard to renounce his kingship?

What really blows my mind is the blind spot Hotspur had in Richard II. He obviously has respect for Edmund Mortimer, a man for whom King Henry IV has deep seated hatred. Hotspur shoots off another long-winded speech defending Mortimer to the king earlier in the play, portraying Mortimer as a bona fide soldier,coming head-to-head with the true rival of Henry IV, Glyndŵr (100). If you look at the tree (or read any of the footnotes), you’ll see that Edmund Mortimer was next in line after Richard II. This became void when Richard voluntarily relinquished his crown to Henry IV. Hotspur had to have known this, yet he continued to help Henry IV in his pursuit to have the throne.

Perhaps I am wrong about this. If Richard kept the crown and died without giving up his crown, Mortimer would have received it, right? I was confused about this during the reading of Richard II as well. If this is true, why did Hotspur assist Henry IV? Was Richard II that bad as a king that he couldn’t wait? To think that now, Hotspur sees Richard as this “lovely rose” and Henry the “canker,” was it worth the overthrow? Or was Henry too powerful at the time, so Hotspur thought ‘if you can’t beat them, join them’?