Overview
GCS stands for Google Search Console which is a program helping one’s site show up on google as well as understanding how google search sees your page. In recent years, GCS (Google Search Console) has gone through many revisions. The “legacy” tools are a bit dated but it still offers a unique and important approach in comparison to the “Report at a glance” tools.
Comparison
One section of the legacy tools allows you to “Lower google crawling traffic to your site”. The “Current Search Console Reports” tool allows you to request a reduced crawl rate. This seems like more of a process, although it also shows you how often google is crawling your site and how many requests it’s making. The URL Parameter tool (Legacy) and URL Inspection tool (Current Search Console Reports) both offer different expertise when it comes to your URL. While “Current Search Console Reports” has many features that are wonderful, it doesn’t allow you to obtain the International Targeting settings, which can be extremely helpful depending on the logistics of your business plan.
While the “Current Search Console Reports” tools are more advanced and updated, I think it may be most effective to still use the two set of tools in a combination so that you can benefit from all resources.They have not eliminated legacy tools because they clearly believe those tools are helpful still despite the newer ones being available. They know both tools have different things to offer, and depending on the user, they may benefit from one over the other, or a combination of both tools. This reminds me of the Paid ads and SEO blog recently as both methods together may be the most successful. I also think there is a small chance they could be temporarily leaving the older tools in the dust despite the different options, but keeping them now for a better transition. This is what Youtube (owned by Google) did with the old uploading service (Youtube Studio).
Benefits
Some benefits of the “Current Search Console Reports” tools are the in depth crawling tracker, performance,coverage, core web vitals and sitemap reports. As well as some of the more modern features it offers such as the Mobile friendly test tool and Mobile usability report, which give you helpful information regarding the newer, mobile side of website development. That is something that wasn’t as crucial when they created Legacy tools. Some benefits with the “legacy” tools are the International Targeting settings, the URL Parameter tool, data highlighter tool and other random web tools.
https://support.google.com/webmasters/answer/9133276?hl=en&ref_topic=4558844