Do you think the theoretical knowledge in marketing is useful or just theories, and real life is different?

Theoretical knowledge is must and is necessary, it has to applied in real life and in the marketing process.
As customer retention has become more of a business priority in our intensifying competitive markets, the marketing function has evolved from influencing potential customers to involving them the company's business planning and advancement.
It prepares the ground for a sales person to approach a consumer.
Marketing as such is not direct and it uses various methods like advertising, brand marketing, public relations, direct mails and viral marketing for creating an awareness of the product THE APPLICATION IN PROCESS REQUIRES PROFESSIONAL KNOWLEDGE.
The process of marketing has to be structured appropriately to effect sales.
Sales functions are inadequate in today's times without marketing and marketing functions cannot be performed without theoretical knowledge.

Anyone who has been intensively involved in marketing activities knows that it is very eco social and geo political. 

FMCG Retailing for example is different and diverse in different part of the world. Applying same theories in Europe and Africa would be totally inappropriate. 

Marketing is a very creative function and if you rely solely on theorical studies.......................

It depends on many factos : Eco-Social , Geo-political.
Theoretical is always useful but with pratices you'll see that there is a large difference.
and i repeat it depends on the market & the geopolitical situation.
:)

theoretical knowledge is good for knowing market skills but no doubt the real market is so different and when any person practice that market experience's he knows that what so ever he learn in theory is quite simple and market is so huge.

Theoretical knowledge is like the base of a building without which you cannot progress far. However, in real life, things are customized according to invidual needs. But the basis of the same is always the theoretical knowledge.

Its necessary to applied in marketing process

Theory is a useful, sometimes very powerful tool, but mostly real world is different from the theory. We could have a utopia if the theories worked

Yes many apply their theoretical knowledge in their marketing