When to Add 了 in the 太....了 Structure
Continuing your example:
if we remove '已经'  


  所以，现在我不太爱坐飞机了


still means 'not anymore' because of '现在'. The reason you say '现在' in this sentence must be to compare past and current, so '已经' is optional in this sentence.  

Now if we also remove '现在'


  所以，我不太爱坐飞机了


Well, it still more or less means 'not anymore', because of the '了'.  '了' here also somewhat implies 'after some incident', similar to '已经'. Ex:


  去年空难之后，我就不太爱坐飞机了


So if you want to state 'I really don't like taking planes due to some reason.', then for example:  


  我有幽闭恐惧症，所以我不太爱坐飞机


would probably translate to 'I always have claustrophobia, so I don't like taking planes.'

but


  我有幽闭恐惧症，所以我不太爱坐飞机了


somewhat implies 'I recently got claustrophobia, so now I don't like taking planes.'