The most well-known legend about why Brahma is not widely worshipped involves his creation of Goddess Saraswati, who emerged from him and whom he found very beautiful. His apparent desire for her, which is often interpreted as symbolic of the mind's pursuit of knowledge, led to a series of events where Shiva (or in some versions, other gods) felt that Brahma’s behavior was inappropriate for a creator deity.
In one version, Shiva, as the enforcer of cosmic order, decapitated one of Brahma's five heads (which represented Brahma's 'ego') for lying about finding the top of the infinite pillar of light. Another version of this story indicates that when Brahma lied to Vishnu about having seen the top of the fiery pillar, he was cursed by Lord Shiva that he would not be revered and worshipped by devotees.
Furthermore, there is a philosophical explanation as well. Brahma, being the creator, represents the aspect of creation which inherently includes change, impermanence, and illusion (Maya). Therefore, he is less relevant to the goals of moksha (liberation) and spiritual enlightenment, which are central to Vedic practice. In contrast, Lord Vishnu and Lord Shiva are associated with the aspects of preservation and destruction/transformation, respectively, which are seen as more directly involved in the cosmic cycle and the spiritual journey of the soul.
Despite these stories, Lord Brahma is still very respected and acknowledged in the Vedic Hindu philosophy and religious practice. This lack of worship does not diminish his importance in Hindu cosmology but rather illustrates the vast and varied tapestry of beliefs, stories, and practices in Vedic Hindu tradition.
Lord Brahma is part of the Trimurti and is recognized for his role in the creation of the universe. However, his temples are rare, with the most famous one being the Brahma Temple in Pushkar, Rajasthan, India.