UKH

Hi. In your experience of 4 season sleeping bags, does the fabric look and stay quite wrinkled.

I have a Rab Expedition 1200 from 2014 and the fabric is very wrinkled. 

Have you tried ironing it?

If it's been stored unused for years then the fabric probably will be wrinkled. Just using it will probably get rid of some of the creases, or open it out and hang it to air.

Check the care label first!!! (Don't do this if it says not to tumble dry)

Put it in a tumble dryer on its own on low/warm with 3 tennis balls and let it run for 15 minutes

Is there a problem with the functionality of the bag, or has it simply taken some of the characteristics of its last inhabitant..........?

Have you been storing them in their stuff sacks, compressed?

I'm not ironing my wrinkled sac

It's fairly normal for polyamides (the fabric most tents, sleeping bags, GTX jackets and indeed a lot of other outdoor gear is made from) to become wrinkled when stuffed for extended periods of time. Some use will easily get rid of the wrinkles (until you stuff them in your pack again...). 

I remember some hot debates at work (I work in outdoor retail) wether it's better to fold or stuff sleeping bags and tents. I don't think there really is something to be said for or against either position. I've done both and it doesn't really seem to make a difference. 

TLDR: yes this is normal but some use will get it out.