One of the most basic reasons to study grammar is to facilitate communication. Lacking proper grammar prevents the full ability to effectively communicate with another human being.   In understanding the rules and tenets of grammar, one is able to access more qualities of language.  Enhancing one's grammar also enables an individual to communicate with greater precision and accuracy.  Language is based upon rules.  When one fails to understand these rules, their communication capacity decreases.  Grammar allows an individual to recognize these rules and appropriate them as part of their daily oral and written expression.  

The implications of not knowing grammar are profound.  Individuals who lack grammar skills are not going to be recognized for professions and professional occupations where grammar usage is essential.  As the world becomes more globalized and where businesses have to adapt to changing linguistic realities, knowledge of grammar can enhance communication with potential clients and thus increase the chance of generating greater income.  This becomes another essential reason why studying grammar is important.

I think that another reason to study grammar is because an increasing number of people are validating its importance.  As languages like English are becoming even more widely appropriated, individuals will have to recognize some basic understanding about the nature of grammar and linguistic expression.  This becomes critical in how individuals can better understand spoken and written language.  Since more people understand more languages, the need to distinguish oneself in understanding grammar rules and syntax ideas become extremely important.