Trying to 'hide' the use of a racist term because you're a racist would be one thing, but using the term in a way that is not at all meant as pejorative is another.

In the automotive context, the term meant something like "Putting loads of pointless mods on your 'shitty' Japanese car that makes it look even uglier and doesn't make it go any faster." - and in that context it was unambiguously a slur, disparaging the Asian import scene in favour of the 'superior' western aesthetic and way of doing things.

But even in the automotive context, people can reclaim the term and say effectively "Yes - my car is 'riced out' - that's the aesthetic I want, and I'm proud of it."

In some ways it's quite appropriate that this term would extend from Japanese cars into tricking out your operating system. Given the number of waifu wallpapers you see in screenshots, 'ricing' has quite a lot of overlap with anime aesthetic, geek cuture and 'weebs' (which is another term that was used as an insult, and now reclaimed by people who proudly describe themselves as such). People who have historically been looked down upon by most of society but internally wear their 'weebdom' as a badge of pride.

It's hardly an insult when you are the one saying it about yourself, and doing so proudly.