Why is that that you can't get a single, normal-sized bag of cheese puffs? If I want to eat a whole bag of Whotsits in one sitting, I should be able to do it without having to go through six tiny individual bags! Seriously, what is up with that??
Depends what you mean by 'normal'-sized. Normal-sized in the US is large-sized in a lot of other countries

. To me, those small bags of Wotsits
are normal-sized - anything bigger is too much for me to eat in one sitting

.
Having said that though, you can get larger/sharing sized packets of crisps like Wotsits - they're around somewhere (particularly in service stations/train stations/airports etc.). You can also get larger, sharing-sized bags of supermarket own brand cheese puffs and the like, whereas the name-brands often don't make large packets..
And seriously, British food manufacturers, FIGURE OUT HOW TO DO RESEALABLE PACKAGING. The "resealable tabs" that stick for like 10 seconds do not count. What reasonable person needs to cook 42 frozen chicken nuggets or an entire bag of frozen peas at once? Just put a freaking ziploc seal on there!
I've never really felt the need for resealable packaging myself - I don't eat a lot of frozen food (the only things in my freezer right now are 2 tubs of Ben and Jerry's and half a loaf of bread), but my parents just seal open bags of frozen food with wire food tags.