This discussion comes up time & again through every brewing forum known to man. Bottom line-kits are fine,if you happy with kits thats fine, they can produce some good brews. There is an initial outlay for AG kit,yes-things aren't cheap.but you don't have to buy shiney or everything at once.With practise (and if you have the time,which can be a major factor) outstanding beer can be made.
If you are baulking at the cost now,wait a few years until 2 can kits start edging towards the £25-30 price bracket. That is one reason why I switched- £20 for a premium 2 can kit or £22 for a sack of malt.
Kit,AG,extract,BIAB-as long as you are happy with what you brew then thats it,why change? If you want to make more individual,cheaper beer then switch. There's no 4 legs good,2 legs bad issue-just personal choice.