Presumably, because a ruling on the outcome allows the parties to take action going forward knowing what the ruling will be, but drafting a written order that is coherent, grammatical, etc. takes more time and care than deciding how to rule. In a complex case, this could easily take several hours of work, even if the judge has very precise notes about the substance of what the ruling will say.
For example, many judges make it a common practice to pull up the appropriate case caption, identify counsel and the parties for each side, establish some defined terms for party or real property or entity names that are pertinent to the case, set forth all jurisdictional facts authorizing the court's action (even if they aren't in dispute), to set forth the names of all of the witnesses, when they testified and what they testified to, to list all of the exhibits admitted into evidence discussing important ones in detail, to recap the principle legal and factual arguments made by the parties, to summarize the overall factual situation, and the recap the procedural posture of the case at the time of the ruling and the undisputed legal principles that apply to the case, and prepare a signature block for the judge, before diving in to discussing and resolving the disputed issues of fact and law that the judge is actually deciding. This anticipatory boilerplate will often make up most of a written court order. In the substance of the part of the ruling resolving disputed issues, references to legal authorities and disputed facts need to be double checked for proper citation form and factual accuracy (e.g. re dates, spelling of names, addresses, dollar amounts, etc.) from notes or other references. Once everything is done, it would usually have to be proofread at least once with at least some minor corrections and changes before the final draft is written and often with headings added or tweaked and formatting issues resolved, even though the ultimate bottom line judgment supported by the judge's notes may simply be that Fred owes Susan five thousand Euros of back rent. The parties already know most of this and don't need these details for their own purposes.
In U.S. courts, it isn't uncommon for a judge to announce a ruling on the outcome immediately following the conclusion of a hearing, having made a decision and then ask a party (or both parties) to prepare a rough draft of a written order setting forth the basis for the decision, after orally discussing key points the judge has reached conclusions upon with the parties in an abbreviated "ugly" oral ruling. Once a draft or draft is presented, the judge may sign it as is, or edit significantly, before signing (I've seen both things happen). I have no idea if Romania follows that practice.
