Hopped kits to unhopped LME is a stepping stone. Start out with the kits but as you improve step up to the LME. Unhopped LME is a good way to improve your knowledge about brewing and will put you on the track to becoming an all grainer. And if you've made this step then your a more advanced brewer then 90% of homebrewers out there.
Keep in mind Kits are not just LME and Hops, they have varying degrees of specialty grains that are added. A beer that is just LME and Hops will lack flavours. Read about steeping grains and you will learn about adding these flavours.
Think of it this way: kits are the TV diner of brewing. everythings there, just heat it up and your done. However they don't taste that good when you compare it to food made from scratch. An unhopped LME beer is the frozen vegies and sausages of brewing, a little bit more effort required then a tv dinner, and a lot more rewarding, but still a lot of room to improve.