You are difinitely correct, SegWit helps to increase the block to the suitable size, but only 20% miners agree with it, the left miners are so selfish, if btc tx is so slow, users won't use it at all, miners will cry, they are too naive to refuse SegWit.
More than 20% and those miners who lingering just wait to test in on Lightcoin.
Litecoin activating segwit is unfortunately not a viable test-scenario, so I don't know where people are drawing conclusion from this.
In any case segwit is safer than BU, it is the next logical step. Bitcoin's segwit is way safer than Litecoin's. In fact, if something goes wrong on Litecoin's wegit, im sure the big blockers will use it to further add more FUD into segwit.