"It is for the deer alone but not its skin..." it is said so in reply. If it were to be for the deerskin, from the view point of Raam, he could have shot his arrow from where he was standing, which miraculously could pierce any terrain, killed the deer, and safely came back into His quiver, as in the case of showing his prowess to Sugreev, later.

Or otherwise, Raam should have turned down the request of Seetaa, as He did in the 9th Sarg of Aranya Kaand, when She was saying: 'Where that weapon? Where this forest? Where the principles of Kshatriya? And where this sagely nature? All this is inconsistent... Let us abide by the laws of the land ...' [Aranya Kaand, Sarg 9, Shlok 27)]. Here He ran after the deer, for that deer lured Him. When kings come into such sort of allurement, many wise men quote this instance as a reminder to them, in Mahaabhaarat.

"Impossible is a Golden Deer's birth", Raam knew that, even then Raam is lured, when time is parlous, even the best man's brain deranges..." Fate harasses the faculty, faculty cannot harass the fate, even the cleverest Raam, went after the Golden Deer... Unborn it was, none had seen yet, nor mentioned about anywhere, such was the mirage of Raam... parlous times cause percipience.

Hence Raam's going after the deer is for the deerskin, on one count, and for the deer itself, on the other, as affirmed by Lakshman because Lakshman never says untruth.

This Maareech was recurrently falling after Raam. Once by an accident, second time as a coincidence, but the third time... a habituation... and it became habitual for Maareech to dare Raam. Hence, Raam had to do something to Maareech, permanently.

The other view according to Pauraanik or mythological sayings is that God endows whatever you seek. But that God alone says: "Seek you will get it, but seek not by the extrinsic values of objects...' [This saying has its counterpart at: "Every one that asketh receiveth; and he that seeketh findeth..." St Matthew, ch. 7, v. 8 - The Bible.]

But "seek something within the nature, according to your nature...  but not the supernatural... for eyes believe the nature of objects..." is the essence here. He or she who seeks beyond means will have to suffer, either by getting it or devoid of it. This is said in innuendo in Aranya Kaand, Sarg 43, Shlok 33 that "the results of pipedreams fill the coffers of Shukra...'

Further, because parlous time has come to Raam and Seetaa, epically, providentially, and episodically, Raam had to move away from Seetaa. While going after the deer, Raam says much to Lakshman about the security of Seetaa and also instructs him that "She is pivotal to our mission...' [He did not say these many farewells while sending Seetaa and Lakshman for hiding in a cave at the time of fighting with Khar, Dooshan, and the 14,000 Raakshas - maybe He knew that Lakshman will be able to protect Her, but this time He did that because He knew that he will surely fail to do his duties] At one time Raam spared Maareech's life in the forest of Taadakaa while guarding Vishwaamitra's ritual Yagya, only to cause Maareech to come now.

Otherwise also, as such, Raam had to go after Maareech, far from Seetaa. Because, Seetaa or Goddess Lakshmee would not let Raam kill anyone in Her presence.