The LS50 has a few frequency response issues, but they are not beaten overall by any studio monitor near the price. As an engineer I can tell you, you cannot look at one single graph and make a conclusion. You have to look at many aspects of performance.
AND yes they’re definitely worth it. Invest in a decent amp. Nothing crazy, but decent. You can look at this review for more details:
https://speakershunter.com/kef-ls50-review/
However, the KEF LS50 Wireless comes with more advanced features that are not available in LS50. The choice is yours!