Just a note, but you aren't really missing vitamins and stuff when you aren't eating lots of carbs. The vast majority you consume are chains of sugars for the most part.
Reducing carbs in your diet has several effects. One, if you reduce but not cut, you are lowering your available energy stores (important when lifting, which I know you do~) and you are more than likely going to notice a lack of oomph in the gym. This highly depends on how much you were consuming in the first place, but unless you go into ketosis (summoning Khane) your body isn't going to switch over and start using other stored energy in anything even approaching a similar manner, so that could be a negative. Two, reducing carb intake (300lbs is a -big- ass dude) in most people is an effective weight loss tool, because by and large people have no fucking idea how much they are consuming on the daily. Starbucks is sugar coffee. White bread is basically sugar without anything else going for it. Soda is sugar water. It's incredibly easy for a lot of people to consume 1/4 to 1/3 of their daily allowed calories on the way to work, before they eat a single thing. Three, in the end, it comes down to managing caloric intake. Foods that are high in carbs tend to be less filling than foods that are high in fats or protein. This translates into less hunger cravings when you "spend" your calories each day on foods that take longer to digest and will keep you feeling sated for longer.
Carbs aren't inherently bad, it's just that people on the fast-food lifestyle or eating pre-packaged shit tend to over-consume the shit out of them compared to their activity levels. If you were one of those guys who drank a couple of sodas/beers each day on top of just eating normal stuff, you were probably 1000ish calories over your needed amounts, which means you steadily get bigger on the average. Simply cutting the "extra" carbs out of a diet usually puts people down into normal levels, where they can eat a sandwich and not gain 1/8th a lb from doing so.
I lost 30lbs from just reducing my overall calorie intake by about 20% (well and lifting/exercising, but that's not really that much compared to diet) across the board. It helped that I wasn't a soda/Starbucks fanatic or had a related caffeine addiction. The people who -need- to cut carbs mostly out of their diet are those poor bastards.
So while I'm not an Atkins proponent, I will say that it's totally safe to add carbs back into your diet and you'll have no ill effects... as long as you keep your lowered caloric totals the same. Just adding breads and coffees and sodas and shit into your diet without changing it will only be a bad thing.