I think you will see lots of seized piston threads on dirt bike forums because they (well the 125s) spend almost all there time at full throttle, add to that much more marginal jetting, poor maintenance, dirt getting in when the air filters changed and you end up with seizure. Look after them properly and they don't normally give problems ( crank rebuild at 80 hours, piston at 10-15).

Remember most dirt bikes are designed for competitive racing, the NSR is a road bike. Yes seizure is caused by lubrication failure but if you have been racing in the sand on your MX bike and its boiled over ( no temperature gauge) the first you will know anything is wrong is when its locked up, if you have no coolant then no amount of 2 stroke oil will save your piston.

Standard NSRs should be fine for 45 minute commute, make sure your oil pump is adjusted correctly,warm her up before thrashing, keep up with the maintenance and hopefully you should have a reliable bike.

I wouldn't fear keeping the NSR wide open for a long time, that's what its designed to do and its much more fun that way.

As for dirt bikes coming in a higher state of tune, not really, Tbm magazine tested a standard 07 KTM 125 exc at 28 hp with the off road tyres on so lets say 30 hp with street tyres, that's half of a derestricted NSR.

Your smokey CRM sounds normal to me, when you give a 2 stroke a good run it burns of all the unburnt oil in the exhaust and makes clouds of smoke.