Kingston, the "late passenger" issue is a concern but I would simply change the gate closing policy so that it closes 5 minutes earlier than present.
I respect your views and even agree with one or two of your points but you are in the minority on this one as most passengers prefer it....hence why some Easyjet competitors use it as a selling point.
Send your business the FR way if you like but if you want to continue travelling the same City pairs then quite often you will be inconvenienced alot more than having an allocated seat.