You need to look at the direction of travel here. Whilst serious offences are increasingly dealt with in less serious ways, trivial offences are increasingly dealt with in more serious ways. Thinking of an unpaid speeding fine, and a warrant related to that, as trivial today, and of little consequence, doesn't mean that it will be trivial tomorrow when the computer dredges up the old offence. You don't want your return in 30 years time with grandchildren in tow to be ruined by this rearing its ugly face. The only sensible thing to do is to grit your teeth, pay the fine and stop worrying about it.