But you keep thinking that giving the airline your hard earned money is working for you! I'll save mine for extra spends on my holiday!
Cool, do as you wish, as will I. Woohoo a whole extra 60, don't all rush at once kids 
Not sure why you need to tell us about non-british tourist operators though, when we are talking about package holidays and British budget airlines?
It does seem daft doesn't it Ledkr, but then there will always be the people that book late, book last, check in last etc and will then kick off when the only seats left are singles/doubles and they want 4 in a row. They will be the delightful passive aggressive ones that say things like "Oh well if you won't move [from your pre-booked and paid for seats] then you will just have to mop up little Johnny's sick/hold his hand when he cries/take him to the toilet"
But there is no way around it really:
If seats were allocated on booking, then the tour operator would lose out if all they could offer closer to the holiday departure was separated seats - people may not book and then they fly a plane with empty seats. Not cost effective - extra costs passed back to consumers.
If seats were allocated at check-in, then people will get to airports earlier and earlier to ensure they got what they wanted. Desks need to be used for other flights, then there is a mad rush at the 2 hour point for people who have been clogging up the aisles for 5 hours. Plus what about the people who have left in plenty of time but then got stuck in traffic? They then kick off when all the seats are booked. If no-one is paying and two families turn up at once, who gets the last seats together? Does the check in desk flip a coin?
The current system is fairest I suppose - allocated seats can be booked 90 days beforehand. I know of people that sit pressing refresh from midnight to ensure they get the exact seats they want. We don't do that, but do make sure we book them the next day - and generally even 8 hours after booking opens more than half the plane is gone.
You pay your money, you take your chance - or not
. It may not be right, but I'll never take the chance where DD is concerned.