The Hebrew lessons and the Hebrew dictionary need to show all vowels for all words; otherwise it is very difficult (if not impossible!) for learners to learn the correct pronunciation of new words.
I agree. I wish the were included. One contributers did comment on a previous discussion say they will consider including them in some capacity on the next version so fingers crossed.
I think especially given the course has limited audio it is important because otherwise you can guess wrong and get into bad habits. For me, using Memrise as well to hear the correct pronounciation has helped, but I wish they included the nikud. I also found this post very helpful https://forum.duolingo.com/comment/7388681/Hebrew-Time-9-Reading-without-vowels
I think the Arabic course includes the Arabic version of vowels (anyone actually doing the course correct me if I am wrong) so maybe they will reconsider the no vowel stance.
I just started using an online dictation website (https://www.speechtexter.com/) to help with pronunciation. If you let the site access your microphone, it will do speech to text translations in Hebrew (switch language to ivrit on the upper right of the page.) I figure that if the computer can understand my Hebrew, hopefully a human can, too. I use this tool some times for the exercises that provide written English and want written Hebrew back. For such exercises, I would translate the written English in my head, speak the Hebrew, and then copy-and-paste the written Hebrew that it produces.