Sometimes you have to use an old fashioned English typewriter to type into another language. And they have accented letters we just don't have on an ordinary typewriters. Like á, é, í, ó, ú, ü, and ñ for example. Sometimes you substitute. As I've already said, the German letter ß can just be written as "ss" in English. Or it does look like a lowercase B. You could do a b and put a vertical line on it somehow. But that would look weird. " kind of looks like the thing on top of the ü. But what about the rest?
I know technically you're not supposed to leave out the accent marks when you type in English. But would anyone really care?
I live in the U.S., but I set my keyboard for U.K. English. However, if I want to type in Spanish, I use the Character Map for the letters that aren't on the keyboard, such as an ñ. I can do the same with the German ss- ß Thing is, I haven't used German since high school. No one to talk to, so it's mostly disappeared on me, except numbers and "ich leibe dich" "Wie gehts". My husband has learned Spanish vicariously. At first, he said he just listened for his name and then he started learning a few words here and there. I'm not fluent, but in comparison.... lol It's easier for me to spell in Spanish than it is in English and I'm not even Latina.
The accents can change the meaning entirely of some words, but most speakers can figure out the meaning. I think the "purpose" of what you're typing would change how much it matters. If you leave accnet marks out for something professional, it really matters. If you leave them out on a text message to a friend, it's really not that big of a deal. That's just my opinion.
It is absolutely important and I think most native speakers would care as a single accent mark can change the entire meaning of a word. For instance in Spanish, esta (this) vs està (he/she is). Or tu (you; singular form) vs tú (your; possessive). Hope this answers your question.