مَا وَدَّعَكَ رَبُّكَ وَمَا قَلَىٰ
Your Lord has not abandoned you, nor has He become displeased.
The suffix -ka in the first clause identifies the addressed person, whereas qalā in the second clause has no separately expressed object. The first clause provides a strong contextual clue for the same relation, which is why omission is a meaningful analytical question here.
Brevity, fluent expression and the ending sound may all be considered when discussing the effect. Establishing one as the sole cause would require further evidence. The grammatical observation and proposed aesthetic motive should not be conflated.