Rick, the older Craftsman Commercial routers are nice. They are designed to work with 1/4" bits. Supposing you did use an adapter to accept 1/2" bits? You are adding the weight of the adapter plus the additional weight of the 1/2"shank bit. The bearings are not designed to stand up to this additional stress. There is also the height limitation. An adapter would remove virtually all of your height adjustment, just to get it above the base plate. You wouldn't be able to get the bit close to the base plate. Keep this good quality router for it's intended uses, it will still do most things you want. If you have limited amounts of work that require a 1/2" collet there is a 2 HP Skil plunge router for around $60 at HD.
"Living in the D" (this means Detroit!)
"It's fine to disagree with other members as long as you respect their opinions"