Moreover, case decensions are very difficult to learn for people from non-case languages. They often exist in addition to verb conjugation for person/number/gender and tense. They have their own divisions into various groups, and irregularities.
Moreover, there are other ways to achieve flexibility in word order, such as particles which agglutinate without tweaking the target word in any way:
The grammar here isn't standard. Usually you'd mark the subject doing the liking with は and the object being liked with が. Both generally function as topic markers in other circumstances, so context is important. You can even occasionally use は to mark the object being liked if you're pointing out one particularly liked thing. Using を to mark a subject of affection is pretty rare and regarded as incorrect/usually just a tongue slip.
Oftentimes in conversation, particles will be completely dropped in a 好き statement. So getting something like "俺、これ好き" (I, this like) isn't uncommon. In that situation, it's the pause marking the subject doing the liking. If the order is reverse, usually the object marker is used, though as in "これすき、俺は" (this like, I).
Japanese grammar is a complex mess. It uses particles and can be orderless, or it can drop many particles (sometimes all) and have everything marked by pauses and timing.
Moreover, there are other ways to achieve flexibility in word order, such as particles which agglutinate without tweaking the target word in any way:
Japanese:
PetrがJanaを好きだ。(Petr-ga Jana-o suki da)
JanaをPetrが好きだ。(Jana-o Petr-ga suki da)
Petrが好きだ...Janaを。(Petr-ga suki da, ... Jana o.)