I was looking at building a Pitborn Tiefling Paladin, and got to looking at the alternate physical features list, which list's changes to appearance and nothing else. Am I missing something, are the alternate features supposed to do anything? If I roll bat ears, did just give up the SLA for bat ears that don't improve my hearing? I haven't found were the Alternative Physical Features change anything other than appearance, which makes me think I'm missing something entirely, since you have to lose your SLA for it.
You give up the SLA primarily for a roll on the Variant Tiefling Abilities table, which does give you something mechanical in exchange.
The roll on the Alternative Physical Features table gives you something that alters your appearance but does not otherwise have any mechanical effect.