It could also help imply motivation for why he rebuilds it all of the sudden. With the reappearance of the Emperor, Kylo might’ve rebuilt it to remind the First Order who is in charge. It’s like his crown, reminiscent to Supreme Leader Snoke’s golden robes.
It also sort of adds to why Kylo senses that Hux is uncomfortable with it. Kylo is flaunting his royalty, which upsets Hux and ties back into his desire to dethrone him. But of course this is all subtext.