Helen Keller was asked whether she'd rather have her sight or her hearing back. She said hearing, because blindness cuts you off from things, but deafness cuts you off from people.

The most important thing we do with hearing is communicate with other people. Being unable to hear means that you're cut off from easy communication with others. Sure, you can still communicate, but it's a challenge. Reading lips is difficult, and learning how to say words you've never heard is also difficult, so your speech might not be entirely clear. By way of contrast, using sign language to communicate is quite fluid and normal. You go from struggling to communicate in a way designed for hearing people, to being entirely comfortable and having mastery when you're in the world of the deaf. Deaf people in a deaf community really have no disability, and actually its a hearing person who has a disability in that world, because the cacophony of sounds is annoying and distracting, while it doesn't bother deaf people at all. Plus, deaf people are much more used to touching and being physically demonstrative than is common in the hearing community. That is, if someone wants your attention in the hearing community, they might say your name. That's not possible in the deaf community--they'll reach out and touch you. And speaking sign language lends itself to being physically demonstrative and making large gestures, which are not as exuberant in the hearing community. All of these factors mean that it's going to be more comfortable for deaf people to hang out with other deaf people. It takes extra effort to be hanging out in the hearing community, and all deaf people do it to some extent, but many feel more comfortable in the deaf community, just as someone whose native language is X may prefer to hang out with other speakers of X rather than speakers of a language that is foreign to them and that they have to expend extra effort to use.

None of these things are true with blind people. The heart of any community is interactions with other people. Blind people do not have these same challenges in interacting with sighted people, they can still do it extremely well, so there's not as much motivation.

I understand this is phrased as a historic question, but this is hardly a question for historians. Nevertheless I happen to have some relevant information. Historians tend to be generalists after all!

Deafness is, as you say, much more of a cultural identity than blindness. Sign languages are proper languages of their own, in which deaf people express their own ideas in a way that is only directly accessible to other people who know sign language, which are mostly other deaf people. Blind people have no unique communication system like that.

And there is a sense in which deaf people are deaf together, but each blind person is blind by himself. Deafness locks you out of broadcast communication, but blindness locks you out of eye contact and other nonverbal communication, a lot of which is not broadcast but one on one communication. The diagnosis of autism is much more common in blind children than in the general population. It is as far as I know unclear what the causal link is between the two, but no such correlation exists for deaf children.

So together I would argue these factors explain why there are vibrant deaf cultures but no comparable blind cultures.