Keep in mind too that the purpose of an HTML entity - or any HTML, for that matter - is to render your text, that is, to show a visual reprentation of it.
That's not the concern of a database. The database's role is to store data as efficiently as possible - and to make it easy to update and to retrieve the data. It's perfectly possible to store, say, an accented letter in 8 or 16 bits. Provided you have an agreed coding system, you can easily translate between the stored characters and the HTML entity at the time you want to display it.
In fact, this is true even without Unicode. It's true that Unicode lets you store a much greater range of characters, but, if that's not a requirement, you can happily use an 8-bit code.