It depends what you are looking for from your punt.
If you are looking for specific PSE elements such as just going for some decent oral or anal, then you may not be too bothered about DFK.
However, in general, for your usual punt, it is absolutely essential for several reasons:
- With it, you feel like you are shagging an enthusiastic civvie for free; without it, you feel like you're fucking a paid prossie like you are.
- It's fucking enjoyable.
- DFK is a real turn on and gets you going; lips-only kissing is a turn off.
- It's a sign of her attitude: If a girl is 'into it' and 'into you', she'll do DFK and if she isn't up for it, then she won't. If she holds back on DFK, she'll hold back generally. That reticence will be evident in her all-round performance, ie lacklusture and it will be clear she's not enjoying it, so neither will you.