That's one reasonable excuse.
For me, I don't really see any need of getting different color hearing aids or other assistive devices. Since these devices are something for everyday use, they should be in a color that's neutral. If the cost was a lot less, then getting more colors would be reasonable.
For instance, glasses are cheaper. It's better to pick a color that looks good with everything. In most cases, it would be black, brown, silver, gold, brass, etc. However, some people feel that they have to "stand out" and get the most unusual color such as pink, red, blue, etc. But, these people usually have more than one glasses and one of them is neutral.
With hearing aids, they're expensive. So, would it look professional going to work with a pink or blue hearing aid? It doesn't match your outfit. It distracts others from communicating with you. If you have special stickers that can come on and off, great. If it's permanent, then why get it?