I like to carry a stove with me when I'm out. If it's with a group then I have the means of making something hot if the need arises. If I'm on my own then it makes me stop, rest, take in the scenery and just enjoy being out in the hills. I once walked with a chap who took a coffee grinder on the hill so he could enjoy a fresh coffee when we stopped. This may be taking things too far,but then I'm not a coffee drinker.
There are several excellent light weight stoves around now that pack down small and don't cost the earth. It's down to personal choice which one will suit you and your needs. Dehydrated food has also come along way and there is much to choose from. Personal preference is for a packet of noodles (because they're always in the cupboard) or a low fat pasta sauce as they only need water and not milk or butter. Modern stoves can boil a litre of water in a matter of minutes, then make a brew, sit back and enjoy it while the main course cooks.
If you are using a stove in the hills make sure you stay safe - stay away from dry grass and find a suitable rock to stand cook on to prevent scorch marks or worse.
Stopping like this for lunch can really enhance your day in the hills. It helps remind you why you went out, enjoy the peace and tranquillity of your surroundings, or the jealous look of fellow walkers as they smell your cooking. Try it one day, plan a long lunch on your next walk and leave squashed sandwiches for another day.