Why would I need Roon?

The Node2i works as a Roon endpoint, so no need to get ride of it. 

You will need some device to run Roon core if you decide to go that way. This can run on a Mac/PC on the same network, or a dedicated music server. I use a dedicated Intel NUC running Roon ROCK (which is Roon's optimized custom operating system), but this isn't required. 

For me, the strengths of Roon are:

Excellent user interface with lots of great content about artists, albums, etc.

Integrating content from multiple sources including my own music library (about 1500 CDs), Tidal, and Qobuz. 

Ability to control and synchronize music playing in multiple zones. I have five zones in my house. Most of the time, I'm playing the same music, but sometimes my wife wants to listen to something different in her office.

Excellent sound quality with DSP processing for upsampling and equalization. I use the upsampling in my main system, and occasionally use equalization, particularly for older recordings that need a little help.

After using for a year, I bought the lifetime subscription. Probably the best value for the dollar of anything I've purchased for my music system. 

I am using a Bryston BDP-2 as a Roon endpoint, connected to my Roon ROCK via ethernet (with an EtherRegen in between), and AES/EBU connection to my Denafrips Terminator.

I did not hear a difference between Roon and Manic Moose, but far prefer Roon for all the reasons mentioned above (UI, library integration, multi-zone support, DSP processing). 

The Denafrips Terminator buffers and reclocks the digital data, even when using an interface with timing signals (like AES/EBU and SPDIF), so perhaps this is why I'm not hearing a difference.

I agree that Spotify offers a better UI than Tidal and Qobuz. Since I can't access my Roon library from my phone, I usually use Spotify with Apple Carplay in the car. I also find it good for finding new music, although Roon Radio has gotten extremely good at recommending new content. 

I think Spotify's search is better than Roon. If I see a recommendation for a song that doesn't include the album information, it's often a lot easier to figure out what album it is on using Spotify than Roon. 

If Spotify offered uncompressed CD quality (let along hi-rez), it would be a lot closer to meeting my needs. But the ability to create a combined library between my ripped CDs, downloaded hi-rez files, Tidal, and Qobuz, makes Roon the clear winner for me.

The ability control multiple zones and have them synchronized when I'm playing the same content is also a big plus, as is having DSP functionality (upsampling and EQ when needed).