I disagree. It's useful to be able to do a full prototype so a superficial understanding is useful, but I don't think there is significant value really learning HTML / CSS.
There is a huge body of information about which version's of which browsers work with which feature. This is one of those cases where specialization pays huge dividends and working with someone who keeps up with this field is really useful. Think of it like accounting it's useful to quickly learn the fundamentals, but knowing how to audit a fortune 500 company is overkill.
PS: The problem with learning HTML / CSS / JavaScript is it's got a short shelf life. You can learn C and come back to it in 20 years but GUI side of things keeps evolving so unless you constantly keep up you are basically starting over when you come back in 5 years.
Our full prototype is earning revenue. Javascript is extending into desktop applications through Webkit and I'd say HTML/CSS/Javascript is the core GUI skillset for anyone who wants to work on next-gen cross platform applications.
If you're working for other people be a specialist. If you're working for yourself you have to be a generalist. Very difficult to effectively manage and coordinate something you don't really understand.
There is a huge body of information about which version's of which browsers work with which feature. This is one of those cases where specialization pays huge dividends and working with someone who keeps up with this field is really useful. Think of it like accounting it's useful to quickly learn the fundamentals, but knowing how to audit a fortune 500 company is overkill.
PS: The problem with learning HTML / CSS / JavaScript is it's got a short shelf life. You can learn C and come back to it in 20 years but GUI side of things keeps evolving so unless you constantly keep up you are basically starting over when you come back in 5 years.