Ytukyg

I want to know why the Vanara never used weapons such as swords, bows, chakras, clubs, etc., since it has always been shown in Valmiki Ramayana that the Vanara as Hanuman and Sugriva used wrestling, used trees as weapons and even the mountains, but never used swords, bows, spears, chakras, etc.

What is the reason for not using these weapons?

You are right in saying Vanaras do not have weapons and maces are for glorification. Using boulders and trees is their choice. There is no rule that they should not use any physical weapon.

As Vanara means a forest ranger, they are highly likely to use trees, boulders as weapons. They are skilled with weaponry but they chose to use trees and mountains. I explained it in an answer of mine to What is Lord Hanuman's weapon of choice from scriptures?.

All of them are the assaulters with stones, and all are the attackers with trees, and all have their nails and claws as their weapons, yet all are experts in missiles. [Balakanda 17-25b, 26a]

They mostly picked up boulders and trees as they are the weapons which they find easily available. We can say that because Hanuman used an iron rod to kill some Rakshasas in Lanka.

Surrounded on all sides by those strong demons, that Hanuma endowed with a great strength seized a huge iron bar belonging to the arched gate. Taking that iron rod, Hanuma killed the demons. That violent Hanuma strolled in the sky, taking that iron rod in his hand, as Garuda the eagle would carrying a serpent in its claws.[5-39-40]

In the war between the Vanaras and Rakshasas, Sugriva, the lord of vanaras, picked up a n iron rod and steel club from the earth surface and hurled it on up on Mahodara.

The valiant Mahodara, who was the tormentator of hostile forces, lacerated Sugreeva with his arrows. That enraged Sugreeva then saw an iron rod on the ground. Swinging that flashing iron rod and showing it to him, Sugreeva killed the excellent horses of Mahodara with that iron rod of terrible speed. [Yuddha Kanda Sarga 97 shloka 16,17]

Thereupon, the spirited Sugreeva took hold of a formidable steel club, entirely decked with gold, from the earth-surface. [Yuddha Kanda Sarga 97 shloka 23]

These weapons club (Musalam), iron rod (Parigha) etc., are not Sugriva's weapons said to be used by Rakshasas several times in the Valmiki Ramayana.

So, it is their choice which weapon to use and fight with immediately. They pick the immediate weapon to fight their opponent. They don't specifically own weapons.

Vanaras used weapons. For example, see the below verse from Yudha Kanda: Sarga 97 of Valmiki Ramayana:

Lifting that steel club, Sugreeva hurled it. Mahodara too hurled another mace on him. Those two weapons, clashing each other, broke and fell on the floor.

I am answering the title of your question only.

Why don't the Vanaras use weapons?

Vanaras used weapons in the war though not their own. As described in Valmiki Ramayana, Yuddha Kanda, Sarga 70, Lord Hanuman killed Trisiras with the sword of Trisiras himself.

स तस्य पततःखड्गम् समाच्चिद्य महा कपिः |

ननाद गिरि सम्काशस् त्रासयन् सर्व नैरृतान् || ६-७०-४४

Hanuma, that large ape, equal to a mountain in size, snatching away that falling sword of Trishira, roared loudly frightening all the demons there.

स तस्य शीर्षाण्य् असिना शितेन |

किरीट जुष्टानि सकुण्डलानि |

क्रुद्धःप्रचिच्चेद सुतो अनिलस्य |

त्वष्टुःसुतस्य इव शिरांसि शक्रः || ६-७०-४७

That enraged Hanuma the son of wind-god chopped off with that sharp sword, his three heads furnished with diadems and ear-rings, like Indra the lord of celestials chopped off the heads of Vishvarupa the son of Tvashta.

In the same chapter Mahaparshva was killed by a monkey Rishabha.

अभिदुद्राव वेगेन गदां तस्य महात्मनः |

ताम् गृहीत्वा गदाम् भीमाम् आविध्य च पुनःपुनः || ६-७०-६४

मत्त अनीकम् महा पार्श्वम् जघान रण मूर्धनि |

The great souled Rishabha quickly ran towards the mace of that mighty Mahaparshva. Seizing that dreadful mace and striking it repeatedly on the floor, he struck it on Mahaparshva in the battle-front.

स स्वया गदया भिन्नो विकीर्ण दशन ईक्षणः |

निपपात महा पार्श्वो वज्र आहत;इव अचलः || ६-७०-६५

Struck by his own mace, that Mahaparshva with his teeth and eyes fallen out, fell down like a mountain struck by a thunderbolt.

Although, sage Valmiki didn't explicitly mentioned anywhere that mace is the default weapon of Lord Hanuman.