That's right, after much thinking over this period of time, Dante realized that his original idea of having a space-only power system was becoming more and more redundant given the enemies he was facing and the situations he entered.
The previous Dante did not know about First Gates nor having an SDI of above 100,000 in all fields. Heck, his biggest goal was just to reach 2000 so he could be with Beatrice intimately.
The current him had a wider scope of view and decided that versatility was more important than raw power. Yes, having all space cores would make even his 1st rank space spells become as strong as, if not stronger, than basic 9th rank spells without a multiplier, but so what?
If we are talking offensive power, his mage system was no longer the first and best option, not to mention that there would be new power systems coming in soon. As such, he was going to use each one of his ten cores to have an element of its own.