I work as a manager in a large Sports Store, and have had many conversations with companies such as Nike, Puma etc as to the sizing and styles of infant/toddler shoes...so I can give you the major reasons as to why many shoe manufacturers make shoes in Velcro. After receiving copious amounts of complaints from customers, I made it a point of passing on the 'feedback' and constantly received the same answers (excuses) over and over again -
1. Young children scrunch their toes up, so Velcro allows the shoe to be easily opened-up by the parent to make sure the child's foot is properly sitting in the shoe. (They put this down to convenience)
2. It is hard for the manufacturers to accommodate all widths/depths (chubbiness) of childrens feet and Velcro is more forgiving and easier to fit around a young childs foot than lacing - lacing actually makes the shoe shallower, putting alot of pressure on the top of a childs foot and making the shoe gape (or have too much of a gap) across the top of the shoe. (They put this down to ensuring a better fit - I say it's because they can't be bothered to provide a range of different fitting styles like they provide adults with)

All in all, I find these to be excuses and have repeatedly told them so! Lachlan is 4mths old now, and I am dreading getting him shoes (and I work in the industry!), your frustrations are best put to good use by writing to the companies and telling them what you think (nobody likes negative feedback), and maybe (just maybe) with enough demand (and by going direct to the manufacturer) we might find that they realise that they could make some serious $ out of providing more appropriate footwear for infants/toddlers. Oh and also please try not to take your frustrations out on the salespeople, they don't have any say in the matter, the managers do the purchasing - and we can only buy what is available to us