Until there is a major problem with centralized apps/platforms/services that shines creates a need for people to transition to decentralized services,
That is already happening (people are becoming more educated about data and it's uses) but we do not need a major problem in centralized platforms, all we need is to get knowledge of how important our data is for businesses. Because if we talk about IOTs (internet of things) that are generating 1,000 Petabytes in one day. Which is just too big but that's another discussion about managing them.
For now, data from social media is one of them and once we get to know the importance of it and how big organizations are using our data for their own purposes will convince people to move to decentralization. Because decentralization will provide fewer data of your activities in compared to centralized ones. Well, this could be another problem in the adoption of Decentralization as it will affect the features that our governments are using from the big dataset.
Most people are committed to the principle of hedonism (enjoyment).
It means, these web3-based products must have a user-friendly interface that will create no problem to perform tasks even for a traditional (non-technical person). But that's have been in the market too, but do not provide the luxury of existing ones, so. you are right.
Centralized services are perceived by people as reliable services, although in fact, they are not. In my opinion, people have to suffer serious financial losses in order to realize the danger of centralized systems.
People are readily suffering serious financial losses by leveraging the centralized system for example in my area there is one bank that is famous for giving inside information about users' accounts and the money in it. I have seen many cases when people withdrew their money from that Bank and got robbed on the way to home. Why? How can those thieves get to know about the money the person has withdrawn? Because someone from the bank has given a tip to those Robbers and this is not a new problem. But if we can make transactions with full anonymity of personal information no one can get to know us in real life so there will be no such cases.
People can not be anonymous through Web, so the decentralization is fake. And 98% of all Web users do not care of anonymity. For example, a lot of people use Gmail, which is not decentralized E mail service.
If your concerns are about the web which is the internet in which different devices are connected to each other for the purpose of sharing information such as making transactions and sending and receiving files which is also a type of transaction. So, what actually we need here is, we want to hide our personal identities so that a bad actor can not target us even if he gets to know what's in the email. That needs encryption and security mechanisms which are provided by blockchain technology so the platforms which ask for Gmail accounts are not the decentralized ones because as you mention email services are not decentralized so anyone could temper with your data but if you use functions like wallet address, which only provide the information about your wallets and how much money you have in your wallet from where you are getting that money and where you are sending that money. These types of information are of very limited use to the bad actors. So I think people can be anonymous through the web if they could hide their identities and many of the experts are doing that which is not liked by authorities.