The Vorlon page says that Vorlons' true appearance is a tenticle creature. That's not true, and probably comes from the episode where someone had a tentacle creature pretending to be a Vorlon. Since hardly anyone outside of the Vorlon themselves had seen a Vorlon before, they couldn't know the difference.
Vorlon are always beings of light, even when unconscious. See The Pilot episode.
The article needs to be changed if it's to be correct.
The author of the series, does this. The Vorlon hide themselves because they look so 'beautiful' to other species... and, other species would recognize them as their basically 'angels.'
It's implied that The Vorlon visited other species, and probably tampred with their evolution, and were seen as angels, gods, or profits among the other species.
It's unknown if the other species see the Vorlon as an angelic form of their species through telepathic intention, or if it's a 'natural' thing that happens for them.
Anyway, the tentacle thing was a show thing, where a tentacle monster was PRETENDING to be a Vorlon, but was not.
And, the author often does these things in the series, to subvert expectations. People would expect them to hide their 'ugliness' when in fact they're hiding their 'beauty.'