As a relatively new player on the server, I can confirm that getting geared up and ready for endgame content is quite the task.. And near impossible if you stay F2P.
Finding a good guild definitely is one of the requirements for that I suppose, but since my friend and I were not interested in joining any guilds (yet), we had no choice but to spend a lot to gear up.
If there was farmable content like these cores that was actually worth farming, new and (near) F2P players would definitely be more motivated to stay.
The argument could be made that this would mean less real income for the server, but I completely disagree.
As Mela stated in the original post, endgame players will still be lazy and impatient, and therefore buy diamonds to buy the cores (or whichever farmable item) with.
Once the new players become endgame, they aswell might be more inclined to buy diamonds to speed things up.