Pros and cons of cycling to work and back 5 days a week?

Was just wondering from a fitness and weight loss perspective. I've been riding to work and back off and on for the past few weeks and enjoying it. But doing Mon-Fri (it's about 14 miles in total, there and back) would probably increase general CV fitness over time and quite probably accelerate weight loss (simply burning more calories) but building muscle would suffer as my legs wouldn't have a day in between to rest and repair (I've always been told that from a gym perspective you need a day between workouts for the body to repair/build). Does this sound about right?
Wondered what the advantages and disadvantages are to cycling every day (well 5 days in a week to be specific) as oppose to every other day, if any?
Ta muchly.

Okay, you bikeradar splitter..

Your body will adapt to whatever you do. You're not riding that much so it won't be like a massive change. If you're some kind of body builder then, fail.
You'd only need a day off if you really smashed yourself up, like in a hardcore training situation or a big gym session.. 7mi each way to/from work isn't really gonna do that.
You have all day at work (assuming you're not manual labour) and all night to recover.
In (cough) training, I ride 6 days a week. I got annoyed taking a day off and started riding 7 days a week, but keeping the speed down on Monday (my rest day). It's doable but when you're doing Sat and Sun >100k on the weekend you start to enjoy the day off. Do you ride on weekends? If not or if it's slow/easy/short then you should be more than fine riding 5 days a week. I have big legs and I like cheese.