1. They still censorship telegram which means they can read messages locally. With new updates whatsapp could have new rules to censor or modify "dangerous" (to them) messages.
2. E2E encryption is implemented now, what about the future?
Previously WhatsApp had subscriptions ($1/yr) and were proudly ad-free. Facebook scrapped subscriptions and is about to add Ads. WhatsApp also never shared your number with anyone; sharing your number with advertisers is undoubtedly corrupting WhatsApp.
Yeah, I actually paid for the 3 year subscription. Now I can't even see the option. It was a big differentiator in my opinion. Their logic was sound too - even at $1 a user they could make a $1bn a year. (Even in developing countries - because of the networking effect - people would have paid that modest fee.)
They can tell all they want, but I won't trust them until I (or someone I trust, e.g. Debian, FSF, etc.) see the code.
Also being end to end encrypted does not block whatsapp from censoring you or your friends/family! See how they "disabled" links to telegram https://orat.io/blog/as-of-today-whatsapp-is-blocking-telegr... and removed the telegram page from facebook.