Different styles are recommended based on measurements, body type, torso length and other preferences.  The styles recommended will mostly be core collection items as those are the most likely styles to have the most positive results.  Sizing for ALL styles is included for every customer so that even if your customer chooses to purchase a style that was not recommended they at least have the right size.  New styles are not usually recommended by default until there's more experience with them so we can be confident of sizing parameters and customer satisfaction.