I live in the UK and until not too long ago, I used to fly between London (LHR) and Boston (BOS) quite often, up to a dozen times a year. Most of these trips to the USA were for short periods, the longest being about a week, but quite a few were literally for a weekend (i.e. flying to USA on Friday evening and flying back to UK on Sunday evening).
For most of these short trips I would only have a 25L backpack with me - with the minimum required stuff - and buying/obtaining anything else in Boston.
Most of the trips (but not all) were with Virgin Atlantic. Not once had I been stopped because I didn't check any bags. Once or twice I was selected for a secondary screening, where they would sift through my backpack - and then let me on the plainplane.
So I can say that not having any checked in luggage is not a problem in itself.
Note that I am a dual British/American citizen - and this may have had some impact.