Zeros don’t always exist at all maturities; there’s much more variety in coupon bonds…
Stripping does involve transaction costs which may be a limit to arbitrage. I’d have to see some numbers to know whether that’s a real limit or not.
Zero coupon bonds have no reinvestment risk, but you can also be paid for taking on reinvestment risk through a spread. If you think that interest rates will rise and the duration is low, you can actually benefit from being exposed to reinvestment risk. Maybe you want to have it.
If you have default risk, you can reduce some of your default risk by having some cash flows (coupons) up front earlier. (this is why a lot of people want to have a bond paying coupons… it forces the company to ensure continuously that there are enough cash flows to cover interest)
If you have income needs, it may be easier to construct them with a sequence of reliable coupons than have to hunt for zeros that mature at just the right time.