Yes, definitely a good idea to find out from a wide range of people, including market attendees what more could be done to entice people to local shops. There are also presumably many people who don't frequent either, but perhaps would - and so more marketing and promotion locally needed.
Local shops definitely need to be made use of or lost and it is great to see high streets attract new small businesses. It just seems mean-spirited to lobby against a popular new market or to moan about it - just because you were there first in establishing a business (which after all is aimed at not only serving a community but generating yourself a profit) doesn't mean you have a devine right to prevent what you choose to perceive as competition