I dont know anythings about Flask, Java, Django, python, php, lua, c++, visual basic, etc. So i think i cannot vote.
I dont know many things, but simply create some webpages with some webpage editor. If it's feature that i think would be nice on Plesk, there are things that i would like.
First of course is that i still keep my url http://sylvain.heliohost.org for the peoples that goes to my free personnal website.
What would be good also is to have back a free auto-updating https:// (secure) ssl certificate, i think that many peoples would like to have this feature. What i think would be also good on Plesk is different PHP versions. For different formula, as search formula, contact form with captcha, etc. Of course the possibility to have old and new html versions. Other feature i think is to have like Heliohost (no advertisers as popups or banners) except if the users want to. To keep the Heliohost Server Monitor "grd" if possible. The possibility to create easy a 404 error page.
Good also to have e-mail creation accounts as on cPanel to send and receive messages. This with the possibility to create some email as noreply@XYZaccountHeliohost that the user choose if (can send and not receive email) to a created account. This for making the user on Heliohost can send messages and autoblock and autodestroy all messages received (so no one can send anythings and cannot reply back) because of virus/spams. An other possibility would be nice on Plesk is that the created email account wanted is that "autoblock and autodestroy" messages that have "any" attachement (virus/etc.) so can receive only text messages and no attachements, no images, etc. Can check from a webbrowser the possibility to go check the e-mail messages, to read, to write, to delete (empty bin) without having the need to access the hosting space; like SquirrelMail, RoundUpMail, etc.
Probably also MySql for peoples that have items to sell. Bandwith meters, hosting meters and different stats meters for user that want to collect data. Have the possibility to have also on Plesk like Java and CSS. Some FTP and SFTP would be nice. Maybe also Python would be nice. An other thing that maybe would be nice is maybe Lua on Plesk, because i notice that more and more peoples like Lua script. It's the things i think about, possibly gonna have later ideas for Plesk.
But as told there is many things i dont know, i still wander how will work Plesk; and if it will be easy and simple for beginners as my self.
One thing for sure i like very much the admins, moderators and peoples that helped me trough time. For my personnal free website. It's been more then 10 years i'm with Heliohost, i am still glad to be with you and still want to be with you. Thank's very much for keeping my url and keeping my free personnal website. Yes, i wander how would look Plesk; and if it will be easy?
A+