For a lot of services, verifying e-mail addresses is primarily a means to filter a majority of spam accounts - think bulletin boards, buy/sell sites, etc. It is by no means perfect, but it's an easy, low-hanging fruit. It is only secondarily a check to see if the user misspelled his or her e-mail address (which is often checked by having two e-mail fields and comparing them).

I would still say that tracking down a misspelled e-mail address or have the user completely confused at the next login (because they don't realise they misspelled it) might be worse than having the break in the registration process.