Byte addressable vs Word addressable
Word addressing means that, the number of lines in the address bus in the processor is lesser than the number of bits in the word itself.

Lets say we have a 4 byte word. (32 bit address space) 

If this machine is byte addressable, then the address bus of the CPU will have 32 lines, which enables it to access each byte in memory.

If this machine is word addressable, then the address bus of the CPU will have 30 lines ($32 - log_{2}4 =30$), which enables it to access memory ONLY in words/chunks of 4 bytes and that too from addresses which are a multiple of the wordsize. 

Now if you ask the CPU to fetch a byte from a particular address, it will first drop the 2 least significant bits(by drop i mean overwrite them with 0's) of the address, fetch a word from the resulting address and return a byte using the 2 least significant bits as an offset within the fetched word.

This causes memory access time to increase, since the CPU has to spend more time modifying the address and processing the fetched word. But it also helps reduce hardware cost since the complexity of the circuits is reduced due to the reduction in address bus lines.

However, this overhead never arises in a byte addressable machine, hence 'byte extracting' is easier.