DES Encryption Algorithm all 64 bits for key instead of 56 bits
Yes, it would be more secure if they were used correctly. But as it would require a substantially different algorithm, you really would not be talking about DES anymore.

Brute forcing usually scales exponentially with the size of the key. However, if the algorithm is substantially altered then it is required to analyze the algorithm again.

Note that AES is both faster and stronger than DES. There is no need to (substantially) alter DES now there are many better algorithms available. 



(Triple) DES is mainly used for backwards compatibility now. The keysize of DES is too small key size to be of practical use; triple DES has a blocksize that is too small to be used for uses in modern modes of encryption (CTR, GCM etc).