In order to increase the block size you must hard-fork and that is quite a risk on a multi billion dollar production network, but even if that was risk-free it causes centralization.
Why? If every transaction is about 250 bytes and you have 4000 transactions in a 1mb block, that means that in order to statisfy 7 billion on-chain transactions per day (1 per person) that will be confirmed every 10 minutes (144blocks per day) you will need a 12gb block size and on each block around 50million transactions.
In a day you will have the blockchain increase by 1.7TB, do you know many people that can afford such a full node? That means that no user will be able to validate his own transactions by running a full node and will have to trust 3rd party services. That is a huge violation of Satoshi's white paper.

Bitcoin is a premium ledger, there is no reason to keep a coffee payment on an immutable premium ledger. Your home ownership might be a good idea to keep on the blockchain, but not your VOD subscription.

In addition, segwit is a malleability fix. Currently, you can create two identical valid transactions (using the same input and output) and have a different transaction hash since the witness is part of the transaction hash. As result, you can't create safe payment channels.
I realize that you want everything to be done on the blockchain, but how's that going to work, for example, for a pay-per-view service? You will have to pay upfront an hour before starting the service and then hope that no one will cheat you out of your subscription. Using a payment channel you will be able to safely pay per second of viewing the video and know that the other side can't just steal all your money.

Payment channels are extremely safe and so is the Lightning Network.

In addition, currently you trust your money with exchanges like Coinbase. Do you think that when you buy bitcoins from someone on Coinbase they do a blockchain transaction? They simply change values on a Sqlite DB. That is done because the blockchain is slow and expensive to use. Give them a safer and cheaper opportunity and both users and exchanges will be safer.

Peace and Love to all :)