I'm going to repeat and rephrase a few things that have been said here, because they bear repeating. There are two things to remember with regard to Provisioners and food.
First, the regen rates that you see on the broker are what the food items would do for you. If you're a Lv. 15 Scrub, and you're looking at Lv. 50 food, it's not going to do any better for you than Lv. 20 food will. However, it is capable of doing much more, if you're the right level range for it. Note that this also holds true for Poisons - their stated damage is how much it'd do in your hands, and if you're well below the level requirement for the poison, it may well state less damage than a poison that is level-appropriate for you.
Second, food and drink is an absolute necessity if you're going to be soloing on Whites or Yellows (or above, something I can't manage personally). Faster regen rates on Health/Power means less downtime. In many cases, if you have appropriate food on hand, your Health/Power will regenerate completely in the time it takes you to go from one encounter to the next.
I have a Provisioner alt. My partner and I live on the 3-hour and 5-hour recipes. My guildmates don't hate them, either. =^_^=
One last point: On some servers, a Provisioner can make a lot of money through the Broker, especially on Freeport-side. There are so few public provisioners, that the long-duration food items and especially the drink items can sell for quite a tidy sum, especially if you don't flood the market all at once.