Now Bitcoin network is very congested.each block is only 1.05 MB（average）.
Why do not people apply the sewgit address to alleviate this situation.
Of course all people that are using Bitcoin wants to use segwit address to make transaction faster and at least to reduce high transaction fees (who does not want to experience it, right?), the only problem is that most of these Bitcoin wallet and exchanges still don't support segwit features until now, especially those wallet/exchanges that often used by Bitcoin users/investors. And there are only few wallet that I know that currently supporting it like trezor, ledger, and electrum. Some wallet will support segwit next year like blockchain.info.
it is also because people don't usually like change, and when it comes down to security and their money they became overly cautious. and SegWit has always been "optional" or as they call it "opt-in", which means you have to choose to use it...