Impersonal "it is" construction

Do not use, or use very sparingly, the impersonal "it is" construction - save it for the weather and the time (it is raining and it is 6 o'clock).

Therefore, I would prefer  you to avoid: It is essential, important, vital, clear, evident, necessary, obligatory, required etc.

The reason is that the "it" is a placeholder (a grammatical  or existential "expletive" is its official name) and pushes the true subject of the sentence into an uncomfortable secondary position.

Consider using the modals instead (can, could, may, might, ought to, need to, should, will, would etc)

• It is necessary to go - We must/should/need to/have to  go
• It is important to read - We/one/I/one ought to read
• It is vital that we tell him - We absolutely must/need to tell him
• It is clear that he understood - He clearly understood
• It is obligatory to wear flip-flops - You/customers/we must wear flip-flops.
• It is evident that this solution is not going to work - This solution will evidently not work 
• It is easy to see why the modals work better than the impersonal construction - You/one/we/the reader etc.  can easily see  why...