The time had not been right to worship in spirit and in truth before the ministry of Jesus.infact,the Old Testament saints couldn't worship God in spirit because they didn't know the spirit of God as we do.only the king,priest and the prophet had the presence of God upon them or with them,they had an anointing from God that came upon them to stand in theses offices and not one of the anointing in the Old Testament was the same thing that occurs under the New Testament,when people were born again and have the spirit of God dwelling on the conside of them.
You find expressions in the old testament where people worshipped before the lord and worshipped him with all their mights,that's because their worship was in the flesh only,they didn't have the spirit,they couldn't worship in the spirit or in the lord,they could only worship before the lord.
They couldn't worship in the power and might of the Holy Spirit,they could only worship with all their mights in order to be a true worshipper of God who is a spirit.We all must worship in spirit and in truth