In the Bhagavad-gita, why does Krishna say women are less intelligent?
Spiritually, both men and women are equal. Materially, however , they each have strengths and weaknesses. First of all, we have to be careful by what we mean when we say "intelligence." The Bhagavad-gita defines Intelligence as knowing matter, spirit and the controller of both. One who doesn't understand the workings of these three things is "less intelligent."
We find, practically in life, that women - as well as those men engaged in business and those who are into working hard - are mostly interested in sense gratification. They are primarily looking for the opposite sex, beauty, fame, wealth, etc. This is true of all living entities that are unaware of the goal of human life, regardless of gender.
Unfortunately, if we examine, we will find that many women are more interested in their bodies - being beautiful, slender, and well dressed - then they are in being Krishna conscious. Of course in this age of Kali the men are getting more and more into material consciousness and therefore the Srimad-Bhagavatam declares that they are lazy, misguided, unfortunate, prone to forget, and always quarreling over nothing. ( SB 1.1.10). This is the nature of this age. If it gives you any consolation, in Kali yuga the situation is becoming reversed - women are becoming more prone to act like men, and men like women - but unfortunately neither are very interested in spiritual life, so both are "less intelligent."
On another level, Krishna is really the only purusha, ("enjoyer," or "male"). Everyone else is meant to be enjoyed by Him and therefore female....so "female," in that sense, refers to anyone, as all are to be enjoyed by Krishna!
Fortunately elsewhere Srila Prabhupada stresses that anyone - man or woman - who takes to Krishna Consciousness is intelligent. (Chaitanya-charitamrita, Adi Lila 7.2.) You can also look in the Teachings of Queen Kunti for more wisdom Srila Prabhupada has to share on this issue.
So, not to worry, in terms of the right to attain pure devotional service the gopis reign supreme, and Srimati Radharani is the best of all devotees, so the women are in the lead.
Chant Hare Krishna and be happy, and you will be most intelligent! "Persons who are very expert and most intelligent in understanding things as they are engage in hearing narrations of the auspicious activities and pastimes of the Lord, which are worth chanting and worth hearing. Such persons do not care even for the highest material benediction, namely liberation, to say nothing of other less important benedictions like the material happiness of the heavenly kingdom." ( Srimad-Bhagavatam, 3.15.38)
Hope this is helpful.