I agree the velcro isn't as secure as a cotter pin being bent. But they should only be bent about 15 degrees, not 180. The other solution is to use split rings. As far as tape, just around the cotter pin not the whole turnbuckle. Another solution is a dab of silicone on the cotter pin end. One of the few uses for silicone on a boat.
Living aboard in Victoria Harbour