basically if you don't use all four fingers on your fretting hand you are going to restrict yourself eventually - the better you get the more challenging the music you will want to play - and even at a fairly basic level you'll find that not using all four fingers on your fretting hand will mean playing all sorts of scales will be a problem. It's not about being selective per se with your fretting fingers it's pure and simple neccessity that without using all 4 fingers you won't be able to stretch to certainly intervals.
All I can say from experience is that it's the hardest finger to get working like all the others but with consistant effort it will come together - as with everything else you learn - it's just down to practice - don't single it out a a big deal - it's just part of the process of getting good - and that takes work - so work on it
Good luck
Mike