Yes, every vote should be counted. But how the heck do you do it in only 5 days?
Here's another way to look at it. What if the candidate you've voted for dies in the middle of the election day?
Also, what about the voters who vote for a candidate based on the candidate's campaign promises, and then the candidate, once elected, fails to deliver on the promises, or even does the opposite? Have those voters been dis-enfranchised?
Technically, yes. However, there is no remedy for this (other than to vote him out in the next election).
By voting early, you are giving up the ability to decide at the last minute in the event that something changes.
Is this perfect and always fair? No. Is this still the best system? Yes.