I agree with Ian, these are definitely worthwhile improvements. I often use a bit of Eileens brass strip of the correct width to form new safety straps, and solder a bit of brass rod on the top rear, which is then glued into a hole drilled in the solebar, which should give it a bit more strength.
You could go further, of course, and substitute etched brake gear etc., but this is a personal choice and what you've done will certainly improve things, and for 'layout wagons', they'll look fine when painted and weathered up, no doubt.