It affects the encounter design.
How? O_o
I mean ... i go through combat, i finish it ... i decide NOT go to rest yet ... i go through another combat, i finish it too ... i decide NOT go to rest yet ... i go through yet another combat, i finish it ... and now i decide to rest.
How the option for me to rest affected those two combats after first one, when i decided not to use them?
It would affect them if i would have decided to rest after first one, or second one ... yes ... but if i didnt?
Or even better wording for same question:
Combat 1 > Combat 2 > Combat 3 > Rest - I choosed to.
Combat 1 > Combat 2 > Combat 3 > Rest - Rules forced me to.
There is same outcome, where is difference?