Yes, producing lenses and frames is a good business decision. Everyone will always need lenses, and therefore will always need frames. Producing the right style of frames is important. A wide variety should always be in stock to attract a wide customer base. Producing quality frames is also important. Not just to attract more customers, but to know you are providing people with improved vision.
Yes, it is a great business model. So many people need glasses to correct vision. Many people around the world need glasses to correct nearsightedness, farsightedness, astigmatism, and other conditions. With such a large percentage of the population requiring eyewear, it makes perfect sense for a business to produce lenses and frames.
In the past it used to be that people could only visit a small number of places to get eye wear such as lenses and frames. As people now want to shop around more people who create business models to add to the industry is a good idea. They will provide a much needed larger market to those who demand it.
The lenses and frames business is a multibillion dollar one worldwide. If you factor in luxury and designer additions, it's definitely a good business model. Any entity which has a major share of that business is very likely to do well. People always need glasses, there's a large aging segment of the population which will need readers etc, and kids eyesight is getting worse due to all the screen time, so glasses are a pretty good bet.